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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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VI(1P) POSIX Programmer's Manual VI(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
vi — screen-oriented (visual) display editor
vi [-rR] [-c command] [-t tagstring] [-w size] [file...]
This utility shall be provided on systems that both support the
User Portability Utilities option and define the POSIX2_CHAR_TERM
symbol. On other systems it is optional.
The vi (visual) utility is a screen-oriented text editor. Only
the open and visual modes of the editor are described in
POSIX.1‐2008; see the line editor ex for additional editing
capabilities used in vi. The user can switch back and forth
between vi and ex and execute ex commands from within vi.
This reference page uses the term edit buffer to describe the
current working text. No specific implementation is implied by
this term. All editing changes are performed on the edit buffer,
and no changes to it shall affect any file until an editor
command writes the file.
When using vi, the terminal screen acts as a window into the
editing buffer. Changes made to the editing buffer shall be
reflected in the screen display; the position of the cursor on
the screen shall indicate the position within the editing buffer.
Certain terminals do not have all the capabilities necessary to
support the complete vi definition. When these commands cannot be
supported on such terminals, this condition shall not produce an
error message such as ``not an editor command'' or report a
syntax error. The implementation may either accept the commands
and produce results on the screen that are the result of an
unsuccessful attempt to meet the requirements of this volume of
POSIX.1‐2017 or report an error describing the terminal-related
deficiency.
The vi utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines, except
that '+' may be recognized as an option delimiter as well as '-'.
The following options shall be supported:
-c command
See the ex command description of the -c option.
-r See the ex command description of the -r option.
-R See the ex command description of the -R option.
-t tagstring
See the ex command description of the -t option.
-w size See the ex command description of the -w option.
See the OPERANDS section of the ex command for a description of
the operands supported by the vi command.
If standard input is not a terminal device, the results are
undefined. The standard input consists of a series of commands
and input text, as described in the EXTENDED DESCRIPTION section.
If a read from the standard input returns an error, or if the
editor detects an end-of-file condition from the standard input,
it shall be equivalent to a SIGHUP asynchronous event.
See the INPUT FILES section of the ex command for a description
of the input files supported by the vi command.
See the ENVIRONMENT VARIABLES section of the ex command for the
environment variables that affect the execution of the vi
command.
See the ASYNCHRONOUS EVENTS section of the ex for the
asynchronous events that affect the execution of the vi command.
If standard output is not a terminal device, undefined results
occur.
Standard output may be used for writing prompts to the user, for
informational messages, and for writing lines from the file.
If standard output is not a terminal device, undefined results
occur.
The standard error shall be used only for diagnostic messages.
See the OUTPUT FILES section of the ex command for a description
of the output files supported by the vi command.
If the terminal does not have the capabilities necessary to
support an unspecified portion of the vi definition,
implementations shall start initially in ex mode or open mode.
Otherwise, after initialization, vi shall be in command mode;
text input mode can be entered by one of several commands used to
insert or change text. In text input mode, <ESC> can be used to
return to command mode; other uses of <ESC> are described later
in this section; see Terminate Command or Input Mode.
Initialization in ex and vi
See Initialization in ex and vi for a description of ex and vi
initialization for the vi utility.
Command Descriptions in vi
The following symbols are used in this reference page to
represent arguments to commands.
buffer See the description of buffer in the EXTENDED DESCRIPTION
section of the ex utility; see Command Descriptions in
ex.
In open and visual mode, when a command synopsis shows
both [buffer] and [count] preceding the command name,
they can be specified in either order.
count A positive integer used as an optional argument to most
commands, either to give a repeat count or as a size.
This argument is optional and shall default to 1 unless
otherwise specified.
The Synopsis lines for the vi commands <control>‐G,
<control>‐L, <control>‐R, <control>‐], %, &, ^, D, m, M,
Q, u, U, and ZZ do not have count as an optional
argument. Regardless, it shall not be an error to specify
a count to these commands, and any specified count shall
be ignored.
motion An optional trailing argument used by the !, <, >, c, d,
and y commands, which is used to indicate the region of
text that shall be affected by the command. The motion
can be either one of the command characters repeated or
one of several other vi commands (listed in the following
table). Each of the applicable commands specifies the
region of text matched by repeating the command; each
command that can be used as a motion command specifies
the region of text it affects.
Commands that take motion arguments operate on either
lines or characters, depending on the circumstances. When
operating on lines, all lines that fall partially or
wholly within the text region specified for the command
shall be affected. When operating on characters, only the
exact characters in the specified text region shall be
affected. Each motion command specifies this
individually.
When commands that may be motion commands are not used as
motion commands, they shall set the current position to
the current line and column as specified.
The following commands shall be valid cursor motion
commands:
<apostrophe> ( - j H
<carriage-return> ) $ k L
<comma> [[ % l M
<control>-H ]] _ n N
<control>-N { ; t T
<control>-P } ? w W
<grave-accent> ^ b B
<newline> + e E
<space> | f F
<zero> / h G
Any count that is specified to a command that has an
associated motion command shall be applied to the motion
command. If a count is applied to both the command and
its associated motion command, the effect shall be
multiplicative.
The following symbols are used in this section to specify
locations in the edit buffer:
current character
The character that is currently indicated by the cursor.
end of a line
The point located between the last non-<newline> (if any)
and the terminating <newline> of a line. For an empty
line, this location coincides with the beginning of the
line.
end of the edit buffer
The location corresponding to the end of the last line in
the edit buffer.
The following symbols are used in this section to specify command
actions:
bigword In the POSIX locale, vi shall recognize four kinds of
bigwords:
1. A maximal sequence of non-<blank> characters preceded
and followed by <blank> characters or the beginning
or end of a line or the edit buffer
2. One or more sequential blank lines
3. The first character in the edit buffer
4. The last non-<newline> in the edit buffer
word In the POSIX locale, vi shall recognize five kinds of
words:
1. A maximal sequence of letters, digits, and
underscores, delimited at both ends by:
-- Characters other than letters, digits, or
underscores
-- The beginning or end of a line
-- The beginning or end of the edit buffer
2. A maximal sequence of characters other than letters,
digits, underscores, or <blank> characters, delimited
at both ends by:
-- A letter, digit, underscore
-- <blank> characters
-- The beginning or end of a line
-- The beginning or end of the edit buffer
3. One or more sequential blank lines
4. The first character in the edit buffer
5. The last non-<newline> in the edit buffer
section boundary
A section boundary is one of the following:
1. A line whose first character is a <form-feed>
2. A line whose first character is an open curly brace
('{')
3. A line whose first character is a <period> and whose
second and third characters match a two-character
pair in the sections edit option (see ex)
4. A line whose first character is a <period> and whose
only other character matches the first character of a
two-character pair in the sections edit option, where
the second character of the two-character pair is a
<space>
5. The first line of the edit buffer
6. The last line of the edit buffer if the last line of
the edit buffer is empty or if it is a ]] or }
command; otherwise, the last non-<newline> of the
last line of the edit buffer
paragraph boundary
A paragraph boundary is one of the following:
1. A section boundary
2. A line whose first character is a <period> and whose
second and third characters match a two-character
pair in the paragraphs edit option (see ex)
3. A line whose first character is a <period> and whose
only other character matches the first character of a
two-character pair in the paragraphs edit option,
where the second character of the two-character pair
is a <space>
4. One or more sequential blank lines
remembered search direction
See the description of remembered search direction in ex.
sentence boundary
A sentence boundary is one of the following:
1. A paragraph boundary
2. The first non-<blank> that occurs after a paragraph
boundary
3. The first non-<blank> that occurs after a <period>
('.'), <exclamation-mark> ('!'), or <question-mark>
('?'), followed by two <space> characters or the end
of a line; any number of closing parenthesis (')'),
closing brackets (']'), double-quote ('"'), or
single-quote (<apostrophe>) characters can appear
between the punctuation mark and the two <space>
characters or end-of-line
In the remainder of the description of the vi utility, the term
``buffer line'' refers to a line in the edit buffer and the term
``display line'' refers to the line or lines on the display
screen used to display one buffer line. The term ``current line''
refers to a specific ``buffer line''.
If there are display lines on the screen for which there are no
corresponding buffer lines because they correspond to lines that
would be after the end of the file, they shall be displayed as a
single <tilde> ('~') character, plus the terminating <newline>.
The last line of the screen shall be used to report errors or
display informational messages. It shall also be used to display
the input for ``line-oriented commands'' (/, ?, :, and !). When
a line-oriented command is executed, the editor shall enter text
input mode on the last line on the screen, using the respective
command characters as prompt characters. (In the case of the !
command, the associated motion shall be entered by the user
before the editor enters text input mode.) The line entered by
the user shall be terminated by a <newline>, a non-<control>‐V-
escaped <carriage-return>, or unescaped <ESC>. It is unspecified
if more characters than require a display width minus one column
number of screen columns can be entered.
If any command is executed that overwrites a portion of the
screen other than the last line of the screen (for example, the
ex suspend or ! commands), other than the ex shell command, the
user shall be prompted for a character before the screen is
refreshed and the edit session continued.
<tab> characters shall take up the number of columns on the
screen set by the tabstop edit option (see ex), unless there are
less than that number of columns before the display margin that
will cause the displayed line to be folded; in this case, they
shall only take up the number of columns up to that boundary.
The cursor shall be placed on the current line and relative to
the current column as specified by each command described in the
following sections.
In open mode, if the current line is not already displayed, then
it shall be displayed.
In visual mode, if the current line is not displayed, then the
lines that are displayed shall be expanded, scrolled, or redrawn
to cause an unspecified portion of the current line to be
displayed. If the screen is redrawn, no more than the number of
display lines specified by the value of the window edit option
shall be displayed (unless the current line cannot be completely
displayed in the number of display lines specified by the window
edit option) and the current line shall be positioned as close to
the center of the displayed lines as possible (within the
constraints imposed by the distance of the line from the
beginning or end of the edit buffer). If the current line is
before the first line in the display and the screen is scrolled,
an unspecified portion of the current line shall be placed on the
first line of the display. If the current line is after the last
line in the display and the screen is scrolled, an unspecified
portion of the current line shall be placed on the last line of
the display.
In visual mode, if a line from the edit buffer (other than the
current line) does not entirely fit into the lines at the bottom
of the display that are available for its presentation, the
editor may choose not to display any portion of the line. The
lines of the display that do not contain text from the edit
buffer for this reason shall each consist of a single '@'
character.
In visual mode, the editor may choose for unspecified reasons to
not update lines in the display to correspond to the underlying
edit buffer text. The lines of the display that do not correctly
correspond to text from the edit buffer for this reason shall
consist of a single '@' character (plus the terminating
<newline>), and the <control>‐R command shall cause the editor to
update the screen to correctly represent the edit buffer.
Open and visual mode commands that set the current column set it
to a column position in the display, and not a character position
in the line. In this case, however, the column position in the
display shall be calculated for an infinite width display; for
example, the column related to a character that is part of a line
that has been folded onto additional screen lines will be offset
from the display line column where the buffer line begins, not
from the beginning of a particular display line.
The display cursor column in the display is based on the value of
the current column, as follows, with each rule applied in turn:
1. If the current column is after the last display line column
used by the displayed line, the display cursor column shall
be set to the last display line column occupied by the last
non-<newline> in the current line; otherwise, the display
cursor column shall be set to the current column.
2. If the character of which some portion is displayed in the
display line column specified by the display cursor column
requires more than a single display line column:
a. If in text input mode, the display cursor column shall be
adjusted to the first display line column in which any
portion of that character is displayed.
b. Otherwise, the display cursor column shall be adjusted to
the last display line column in which any portion of that
character is displayed.
The current column shall not be changed by these adjustments to
the display cursor column.
If an error occurs during the parsing or execution of a vi
command:
* The terminal shall be alerted. Execution of the vi command
shall stop, and the cursor (for example, the current line and
column) shall not be further modified.
* Unless otherwise specified by the following command sections,
it is unspecified whether an informational message shall be
displayed.
* Any partially entered vi command shall be discarded.
* If the vi command resulted from a map expansion, all
characters from that map expansion shall be discarded, except
as otherwise specified by the map command (see ex).
* If the vi command resulted from the execution of a buffer, no
further commands caused by the execution of the buffer shall
be executed.
Page Backwards
Synopsis:
[count] <control>-B
If in open mode, the <control>‐B command shall behave identically
to the z command. Otherwise, if the current line is the first
line of the edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where
the last line of the display shall be some portion of:
(current first line) -1
otherwise, display a screen where the first line of the display
shall be some portion of:
(current first line) - count x ((window edit option) -2)
If this calculation would result in a line that is before the
first line of the edit buffer, the first line of the display
shall display some portion of the first line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the last line of the display; otherwise, set to
(line - the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Scroll Forward
Synopsis:
[count] <control>-D
If the current line is the last line of the edit buffer, it shall
be an error.
If no count is specified, count shall default to the count
associated with the previous <control>‐D or <control>‐U command.
If there was no previous <control>‐D or <control>‐U command,
count shall default to the value of the scroll edit option.
If in open mode, write lines starting with the line after the
current line, until count lines or the last line of the file have
been written.
Current line: If the current line + count is past the last line
of the edit buffer, set to the last line of the edit buffer;
otherwise, set to the current line + count.
Current column: Set to non-<blank>.
Scroll Forward by Line
Synopsis:
[count] <control>-E
Display the line count lines after the last line currently
displayed.
If the last line of the edit buffer is displayed, it shall be an
error. If there is no line count lines after the last line
currently displayed, the last line of the display shall display
some portion of the last line of the edit buffer.
Current line: Unchanged if the previous current character is
displayed; otherwise, set to the first line displayed.
Current column: Unchanged.
Page Forward
Synopsis:
[count] <control>-F
If in open mode, the <control>‐F command shall behave identically
to the z command. Otherwise, if the current line is the last line
of the edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where
the first line of the display shall be some portion of:
(current last line) +1
otherwise, display a screen where the first line of the display
shall be some portion of:
(current first line) + count x ((window edit option) -2)
If this calculation would result in a line that is after the last
line of the edit buffer, the last line of the display shall
display some portion of the last line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the first line of the display; otherwise, set to
(line + the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Display Information
Synopsis:
<control>-G
This command shall be equivalent to the ex file command.
Move Cursor Backwards
Synopsis:
[count] <control>-H
[count] h
the current erase character (see stty)
If there are no characters before the current character on the
current line, it shall be an error. If there are less than count
previous characters on the current line, count shall be adjusted
to the number of previous characters on the line.
If used as a motion command:
1. The text region shall be from the character before the
starting cursor up to and including the countth character
before the starting cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to (column - the number of columns occupied
by count characters ending with the previous current column).
Move Down
Synopsis:
[count] <newline>
[count] <control>-J
[count] <control>-M
[count] <control>-N
[count] j
[count] <carriage-return>
[count] +
If there are less than count lines after the current line in the
edit buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the next
count - 1 lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line+ count.
Current column: Set to non-<blank> for the <carriage-return>,
<control>‐M, and + commands; otherwise, unchanged.
Clear and Redisplay
Synopsis:
<control>-L
If in open mode, clear the screen and redisplay the current line.
Otherwise, clear and redisplay the screen.
Current line: Unchanged.
Current column: Unchanged.
Move Up
Synopsis:
[count] <control>-P
[count] k
[count] -
If there are less than count lines before the current line in the
edit buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the
previous count lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line - count.
Current column: Set to non-<blank> for the - command; otherwise,
unchanged.
Redraw Screen
Synopsis:
<control>-R
If any lines have been deleted from the display screen and
flagged as deleted on the terminal using the @ convention (see
the beginning of the EXTENDED DESCRIPTION section), they shall be
redisplayed to match the contents of the edit buffer.
It is unspecified whether lines flagged with @ because they do
not fit on the terminal display shall be affected.
Current line: Unchanged.
Current column: Unchanged.
Scroll Backward
Synopsis:
[count] <control>-U
If the current line is the first line of the edit buffer, it
shall be an error.
If no count is specified, count shall default to the count
associated with the previous <control>‐D or <control>‐U command.
If there was no previous <control>‐D or <control>‐U command,
count shall default to the value of the scroll edit option.
Current line: If count is greater than the current line, set to
1; otherwise, set to the current line - count.
Current column: Set to non-<blank>.
Scroll Backward by Line
Synopsis:
[count] <control>-Y
Display the line count lines before the first line currently
displayed.
If the current line is the first line of the edit buffer, it
shall be an error. If this calculation would result in a line
that is before the first line of the edit buffer, the first line
of the display shall display some portion of the first line of
the edit buffer.
Current line: Unchanged if the previous current character is
displayed; otherwise, set to the first line displayed.
Current column: Unchanged.
Edit the Alternate File
Synopsis:
<control>-^
This command shall be equivalent to the ex edit command, with the
alternate pathname as its argument.
Terminate Command or Input Mode
Synopsis:
<ESC>
If a partial vi command (as defined by at least one, non-count
character) has been entered, discard the count and the command
character(s).
Otherwise, if no command characters have been entered, and the
<ESC> was the result of a map expansion, the terminal shall be
alerted and the <ESC> character shall be discarded, but it shall
not be an error.
Otherwise, it shall be an error.
Current line: Unchanged.
Current column: Unchanged.
Search for tagstring
Synopsis:
<control>-]
If the current character is not a word or <blank>, it shall be an
error.
This command shall be equivalent to the ex tag command, with the
argument to that command defined as follows.
If the current character is a <blank>:
1. Skip all <blank> characters after the cursor up to the end of
the line.
2. If the end of the line is reached, it shall be an error.
Then, the argument to the ex tag command shall be the current
character and all subsequent characters, up to the first non-word
character or the end of the line.
Move Cursor Forward
Synopsis:
[count] <space>
[count] l (ell)
If there are less than count non-<newline> characters after the
cursor on the current line, count shall be adjusted to the number
of non-<newline> characters after the cursor on the line.
If used as a motion command:
1. If the current or countth character after the cursor is the
last non-<newline> in the line, the text region shall be
comprised of the current character up to and including the
last non-<newline> in the line. Otherwise, the text region
shall be from the current character up to, but not including,
the countth character after the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
If there are no non-<newline> characters after the current
character on the current line, it shall be an error.
Current line: Unchanged.
Current column: Set to the last column that displays any portion
of the countth character after the current character.
Replace Text with Results from Shell Command
Synopsis:
[count] ! motion shell-commands <newline>
If the motion command is the ! command repeated:
1. If the edit buffer is empty and no count was supplied, the
command shall be the equivalent of the ex :read ! command,
with the text input, and no text shall be copied to any
buffer.
2. Otherwise:
a. If there are less than count -1 lines after the current
line in the edit buffer, it shall be an error.
b. The text region shall be from the current line up to and
including the next count -1 lines.
Otherwise, the text region shall be the lines in which any
character of the text region specified by the motion command
appear.
Any text copied to a buffer shall be in line mode.
This command shall be equivalent to the ex ! command for the
specified lines.
Move Cursor to End-of-Line
Synopsis:
[count] $
It shall be an error if there are less than (count -1) lines
after the current line in the edit buffer.
If used as a motion command:
1. If count is 1:
a. It shall be an error if the line is empty.
b. Otherwise, the text region shall consist of all
characters from the starting cursor to the last
non-<newline> in the line, inclusive, and any text copied
to a buffer shall be in character mode.
2. Otherwise, if the starting cursor position is at or before
the first non-<blank> in the line, the text region shall
consist of the current and the next count -1 lines, and any
text saved to a buffer shall be in line mode.
3. Otherwise, the text region shall consist of all characters
from the starting cursor to the last non-<newline> in the
line that is count -1 lines forward from the current line,
and any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the current line + count-1.
Current column: The current column is set to the last display
line column of the last non-<newline> in the line, or column
position 1 if the line is empty.
The current column shall be adjusted to be on the last display
line column of the last non-<newline> of the current line as
subsequent commands change the current line, until a command
changes the current column.
Move to Matching Character
Synopsis:
%
If the character at the current position is not a parenthesis,
bracket, or curly brace, search forward in the line to the first
one of those characters. If no such character is found, it shall
be an error.
The matching character shall be the parenthesis, bracket, or
curly brace matching the parenthesis, bracket, or curly brace,
respectively, that was at the current position or that was found
on the current line.
Matching shall be determined as follows, for an open parenthesis:
1. Set a counter to 1.
2. Search forwards until a parenthesis is found or the end of
the edit buffer is reached.
3. If the end of the edit buffer is reached, it shall be an
error.
4. If an open parenthesis is found, increment the counter by 1.
5. If a close parenthesis is found, decrement the counter by 1.
6. If the counter is zero, the current character is the matching
character.
Matching for a close parenthesis shall be equivalent, except that
the search shall be backwards, from the starting character to the
beginning of the buffer, a close parenthesis shall increment the
counter by 1, and an open parenthesis shall decrement the counter
by 1.
Matching for brackets and curly braces shall be equivalent,
except that searching shall be done for open and close brackets
or open and close curly braces. It is implementation-defined
whether other characters are searched for and matched as well.
If used as a motion command:
1. If the matching cursor was after the starting cursor in the
edit buffer, and the starting cursor position was at or
before the first non-<blank> non-<newline> in the starting
line, and the matching cursor position was at or after the
last non-<blank> non-<newline> in the matching line, the text
region shall consist of the current line to the matching
line, inclusive, and any text copied to a buffer shall be in
line mode.
2. If the matching cursor was before the starting cursor in the
edit buffer, and the starting cursor position was at or after
the last non-<blank> non-<newline> in the starting line, and
the matching cursor position was at or before the first
non-<blank> non-<newline> in the matching line, the text
region shall consist of the current line to the matching
line, inclusive, and any text copied to a buffer shall be in
line mode.
3. Otherwise, the text region shall consist of the starting
character to the matching character, inclusive, and any text
copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line where the matching character is
located.
Current column: Set to the last column where any portion of the
matching character is displayed.
Repeat Substitution
Synopsis:
&
Repeat the previous substitution command. This command shall be
equivalent to the ex & command with the current line as its
addresses, and without options, count, or flags.
Return to Previous Context at Beginning of Line
Synopsis:
' character
It shall be an error if there is no line in the edit buffer
marked by character.
If used as a motion command:
1. If the starting cursor is after the marked cursor, then the
locations of the starting cursor and the marked cursor in the
edit buffer shall be logically swapped.
2. The text region shall consist of the starting line up to and
including the marked line, and any text copied to a buffer
shall be in line mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to non-<blank>.
Return to Previous Context
Synopsis:
` character
It shall be an error if the marked line is no longer in the edit
buffer. If the marked line no longer contains a character in the
saved numbered character position, it shall be as if the marked
position is the first non-<blank>.
If used as a motion command:
1. It shall be an error if the marked cursor references the same
character in the edit buffer as the starting cursor.
2. If the starting cursor is after the marked cursor, then the
locations of the starting cursor and the marked cursor in the
edit buffer shall be logically swapped.
3. If the starting line is empty or the starting cursor is at or
before the first non-<blank> non-<newline> of the starting
line, and the marked cursor line is empty or the marked
cursor references the first character of the marked cursor
line, the text region shall consist of all lines containing
characters from the starting cursor to the line before the
marked cursor line, inclusive, and any text copied to a
buffer shall be in line mode.
4. Otherwise, if the marked cursor line is empty or the marked
cursor references a character at or before the first
non-<blank> non-<newline> of the marked cursor line, the
region of text shall be from the starting cursor to the last
non-<newline> of the line before the marked cursor line,
inclusive, and any text copied to a buffer shall be in
character mode.
5. Otherwise, the region of text shall be from the starting
cursor (inclusive), to the marked cursor (exclusive), and any
text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to the last column in which any portion of
the character referenced by the mark is displayed.
Return to Previous Section
Synopsis:
[count] [[
Move the cursor backward through the edit buffer to the first
character of the previous section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the
starting line or the starting line was empty, and the first
character of the boundary was the first character of the
boundary line, the text region shall consist of the current
line up to and including the line where the countth next
boundary starts, and any text copied to a buffer shall be in
line mode.
2. If the boundary was the last line of the edit buffer or the
last non-<newline> of the last line of the edit buffer, the
text region shall consist of the last character in the edit
buffer up to and including the starting character, and any
text saved to a buffer shall be in character mode.
3. Otherwise, the text region shall consist of the starting
character up to but not including the first character in the
countth next boundary, and any text copied to a buffer shall
be in character mode.
If not used as a motion command:
Current line: Set to the line where the countth next boundary in
the edit buffer starts.
Current column: Set to the last column in which any portion of
the first character of the countth next boundary is displayed, or
column position 1 if the line is empty.
Move to Next Section
Synopsis:
[count] ]]
Move the cursor forward through the edit buffer to the first
character of the next section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the
starting line or the starting line was empty, and the first
character of the boundary was the first character of the
boundary line, the text region shall consist of the current
line up to and including the line where the countth previous
boundary starts, and any text copied to a buffer shall be in
line mode.
2. If the boundary was the first line of the edit buffer, the
text region shall consist of the first character in the edit
buffer up to but not including the starting character, and
any text copied to a buffer shall be in character mode.
3. Otherwise, the text region shall consist of the first
character in the countth previous section boundary up to but
not including the starting character, and any text copied to
a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line where the countth previous boundary
in the edit buffer starts.
Current column: Set to the last column in which any portion of
the first character of the countth previous boundary is
displayed, or column position 1 if the line is empty.
Move to First Non-<blank> Position on Current Line
Synopsis:
^
If used as a motion command:
1. If the line has no non-<blank> non-<newline> characters, or
if the cursor is at the first non-<blank> non-<newline> of
the line, it shall be an error.
2. If the cursor is before the first non-<blank> non-<newline>
of the line, the text region shall be comprised of the
current character, up to, but not including, the first
non-<blank> non-<newline> of the line.
3. If the cursor is after the first non-<blank> non-<newline> of
the line, the text region shall be from the character before
the starting cursor up to and including the first non-<blank>
non-<newline> of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to non-<blank>.
Current and Line Above
Synopsis:
[count] _
If there are less than count -1 lines after the current line in
the edit buffer, it shall be an error.
If used as a motion command:
1. If count is less than 2, the text region shall be the current
line.
2. Otherwise, the text region shall include the starting line
and the next count -1 lines.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line + count -1.
Current column: Set to non-<blank>.
Move Back to Beginning of Sentence
Synopsis:
[count] (
Move backward to the beginning of a sentence. This command shall
be equivalent to the [[ command, with the exception that sentence
boundaries shall be used instead of section boundaries.
Move Forward to Beginning of Sentence
Synopsis:
[count] )
Move forward to the beginning of a sentence. This command shall
be equivalent to the ]] command, with the exception that sentence
boundaries shall be used instead of section boundaries.
Move Back to Preceding Paragraph
Synopsis:
[count] {
Move back to the beginning of the preceding paragraph. This
command shall be equivalent to the [[ command, with the exception
that paragraph boundaries shall be used instead of section
boundaries.
Move Forward to Next Paragraph
Synopsis:
[count] }
Move forward to the beginning of the next paragraph. This command
shall be equivalent to the ]] command, with the exception that
paragraph boundaries shall be used instead of section boundaries.
Move to Specific Column Position
Synopsis:
[count] |
For the purposes of this command, lines that are too long for the
current display and that have been folded shall be treated as
having a single, 1-based, number of columns.
If there are less than count columns in which characters from the
current line are displayed on the screen, count shall be adjusted
to be the last column in which any portion of the line is
displayed on the screen.
If used as a motion command:
1. If the line is empty, or the cursor character is the same as
the character on the countth column of the line, it shall be
an error.
2. If the cursor is before the countth column of the line, the
text region shall be comprised of the current character, up
to but not including the character on the countth column of
the line.
3. If the cursor is after the countth column of the line, the
text region shall be from the character before the starting
cursor up to and including the character on the countth
column of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of
the character that is displayed in the count column of the line
is displayed.
Reverse Find Character
Synopsis:
[count] ,
If the last F, f, T, or t command was F, f, T, or t, this command
shall be equivalent to an f, F, t, or T command, respectively,
with the specified count and the same search character.
If there was no previous F, f, T, or t command, it shall be an
error.
Repeat
Synopsis:
[count] .
Repeat the last !, <, >, A, C, D, I, J, O, P, R, S, X, Y, a, c,
d, i, o, p, r, s, x, y, or ~ command. It shall be an error if
none of these commands have been executed. Commands (other than
commands that enter text input mode) executed as a result of map
expansions, shall not change the value of the last repeatable
command.
Repeated commands with associated motion commands shall repeat
the motion command as well; however, any specified count shall
replace the count(s) that were originally specified to the
repeated command or its associated motion command.
If the motion component of the repeated command is f, F, t, or T,
the repeated command shall not set the remembered search
character for the ; and , commands.
If the repeated command is p or P, and the buffer associated with
that command was a numeric buffer named with a number less than
9, the buffer associated with the repeated command shall be set
to be the buffer named by the name of the previous buffer
logically incremented by 1.
If the repeated character is a text input command, the input text
associated with that command is repeated literally:
* Input characters are neither macro or abbreviation-expanded.
* Input characters are not interpreted in any special way with
the exception that <newline>, <carriage-return>, and
<control>‐T behave as described in Input Mode Commands in vi.
Current line: Set as described for the repeated command.
Current column: Set as described for the repeated command.
Find Regular Expression
Synopsis:
/
If the input line contains no non-<newline> characters, it shall
be equivalent to a line containing only the last regular
expression encountered. The enhanced regular expressions
supported by vi are described in Regular Expressions in ex.
Otherwise, the line shall be interpreted as one or more regular
expressions, optionally followed by an address offset or a vi z
command.
If the regular expression is not the last regular expression on
the line, or if a line offset or z command is specified, the
regular expression shall be terminated by an unescaped '/'
character, which shall not be used as part of the regular
expression. If the regular expression is not the first regular
expression on the line, it shall be preceded by zero or more
<blank> characters, a <semicolon>, zero or more <blank>
characters, and a leading '/' character, which shall not be
interpreted as part of the regular expression. It shall be an
error to precede any regular expression with any characters other
than these.
Each search shall begin from the character after the first
character of the last match (or, if it is the first search, after
the cursor). If the wrapscan edit option is set, the search shall
continue to the character before the starting cursor character;
otherwise, to the end of the edit buffer. It shall be an error if
any search fails to find a match, and an informational message to
this effect shall be displayed.
An optional address offset (see Addressing in ex) can be
specified after the last regular expression by including a
trailing '/' character after the regular expression and
specifying the address offset. This offset will be from the line
containing the match for the last regular expression specified.
It shall be an error if the line offset would indicate a line
address less than 1 or greater than the last line in the edit
buffer. An address offset of zero shall be supported. It shall be
an error to follow the address offset with any other characters
than <blank> characters.
If not used as a motion command, an optional z command (see
Redraw Window) can be specified after the last regular expression
by including a trailing '/' character after the regular
expression, zero or more <blank> characters, a 'z', zero or more
<blank> characters, an optional new window edit option value,
zero or more <blank> characters, and a location character. The
effect shall be as if the z command was executed after the /
command. It shall be an error to follow the z command with any
other characters than <blank> characters.
The remembered search direction shall be set to forward.
If used as a motion command:
1. It shall be an error if the last match references the same
character in the edit buffer as the starting cursor.
2. If any address offset is specified, the last match shall be
adjusted by the specified offset as described previously.
3. If the starting cursor is after the last match, then the
locations of the starting cursor and the last match in the
edit buffer shall be logically swapped.
4. If any address offset is specified, the text region shall
consist of all lines containing characters from the starting
cursor to the last match line, inclusive, and any text copied
to a buffer shall be in line mode.
5. Otherwise, if the starting line is empty or the starting
cursor is at or before the first non-<blank> non-<newline> of
the starting line, and the last match line is empty or the
last match starts at the first character of the last match
line, the text region shall consist of all lines containing
characters from the starting cursor to the line before the
last match line, inclusive, and any text copied to a buffer
shall be in line mode.
6. Otherwise, if the last match line is empty or the last match
begins at a character at or before the first non-<blank>
non-<newline> of the last match line, the region of text
shall be from the current cursor to the last non-<newline> of
the line before the last match line, inclusive, and any text
copied to a buffer shall be in character mode.
7. Otherwise, the region of text shall be from the current
cursor (inclusive), to the first character of the last match
(exclusive), and any text copied to a buffer shall be in
character mode.
If not used as a motion command:
Current line: If a match is found, set to the last matched line
plus the address offset, if any; otherwise, unchanged.
Current column: Set to the last column on which any portion of
the first character in the last matched string is displayed, if a
match is found; otherwise, unchanged.
Move to First Character in Line
Synopsis:
0 (zero)
Move to the first character on the current line. The character
'0' shall not be interpreted as a command if it is immediately
preceded by a digit.
If used as a motion command:
1. If the cursor character is the first character in the line,
it shall be an error.
2. The text region shall be from the character before the cursor
character up to and including the first character in the
line.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: The last column in which any portion of the first
character in the line is displayed, or if the line is empty,
unchanged.
Execute an ex Command
Synopsis:
:
Execute one or more ex commands.
If any portion of the screen other than the last line of the
screen was overwritten by any ex command (except shell), vi shall
display a message indicating that it is waiting for an input from
the user, and shall then read a character. This action may also
be taken for other, unspecified reasons.
If the next character entered is a ':', another ex command shall
be accepted and executed. Any other character shall cause the
screen to be refreshed and vi shall return to command mode.
Current line: As specified for the ex command.
Current column: As specified for the ex command.
Repeat Find
Synopsis:
[count] ;
This command shall be equivalent to the last F, f, T, or t
command, with the specified count, and with the same search
character used for the last F, f, T, or t command. If there was
no previous F, f, T, or t command, it shall be an error.
Shift Left
Synopsis:
[count] < motion
If the motion command is the < command repeated:
1. If there are less than count -1 lines after the current line
in the edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and
including the next count -1 lines.
Shift any line in the text region specified by the count and
motion command one shiftwidth (see the ex shiftwidth option)
toward the start of the line, as described by the ex < command.
The unshifted lines shall be copied to the unnamed buffer in line
mode.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to
the first line in the edit buffer that is part of the text region
specified by the motion command.
Current column: Set to non-<blank>.
Shift Right
Synopsis:
[count] > motion
If the motion command is the > command repeated:
1. If there are less than count -1 lines after the current line
in the edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and
including the next count -1 lines.
Shift any line with characters in the text region specified by
the count and motion command one shiftwidth (see the ex
shiftwidth option) away from the start of the line, as described
by the ex > command. The unshifted lines shall be copied into the
unnamed buffer in line mode.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to
the first line in the edit buffer that is part of the text region
specified by the motion command.
Current column: Set to non-<blank>.
Scan Backwards for Regular Expression
Synopsis:
?
Scan backwards; the ? command shall be equivalent to the /
command (see Find Regular Expression) with the following
exceptions:
1. The input prompt shall be a '?'.
2. Each search shall begin from the character before the first
character of the last match (or, if it is the first search,
the character before the cursor character).
3. The search direction shall be from the cursor toward the
beginning of the edit buffer, and the wrapscan edit option
shall affect whether the search wraps to the end of the edit
buffer and continues.
4. The remembered search direction shall be set to backward.
Execute
Synopsis:
@buffer
If the buffer is specified as @, the last buffer executed shall
be used. If no previous buffer has been executed, it shall be an
error.
Behave as if the contents of the named buffer were entered as
standard input. After each line of a line-mode buffer, and all
but the last line of a character mode buffer, behave as if a
<newline> were entered as standard input.
If an error occurs during this process, an error message shall be
written, and no more characters resulting from the execution of
this command shall be processed.
If a count is specified, behave as if that count were entered as
user input before the characters from the @ buffer were entered.
Current line: As specified for the individual commands.
Current column: As specified for the individual commands.
Reverse Case
Synopsis:
[count] ~
Reverse the case of the current character and the next count -1
characters, such that lowercase characters that have uppercase
counterparts shall be changed to uppercase characters, and
uppercase characters that have lowercase counterparts shall be
changed to lowercase characters, as prescribed by the current
locale. No other characters shall be affected by this command.
If there are less than count -1 characters after the cursor in
the edit buffer, count shall be adjusted to the number of
characters after the cursor in the edit buffer minus 1.
For the purposes of this command, the next character after the
last non-<newline> on the line shall be the next character in the
edit buffer.
Current line: Set to the line including the (count-1)th character
after the cursor.
Current column: Set to the last column in which any portion of
the (count-1)th character after the cursor is displayed.
Append
Synopsis:
[count] a
Enter text input mode after the current cursor position. No
characters already in the edit buffer shall be affected by this
command. A count shall cause the input text to be appended count
-1 more times to the end of the input.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Append at End-of-Line
Synopsis:
[count] A
This command shall be equivalent to the vi command:
$ [ count ] a
(see Append).
Move Backward to Preceding Word
Synopsis:
[count] b
With the exception that words are used as the delimiter instead
of bigwords, this command shall be equivalent to the B command.
Move Backward to Preceding Bigword
Synopsis:
[count] B
If the edit buffer is empty or the cursor is on the first
character of the edit buffer, it shall be an error. If less than
count bigwords begin between the cursor and the start of the edit
buffer, count shall be adjusted to the number of bigword
beginnings between the cursor and the start of the edit buffer.
If used as a motion command:
1. The text region shall be from the first character of the
countth previous bigword beginning up to but not including
the cursor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the
first character of the countth previous bigword is displayed.
Change
Synopsis:
[buffer][count] c motion
If the motion command is the c command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count -1 lines after the current line
in the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count -1 lines.
Otherwise, the buffer text mode and text region shall be as
specified by the motion command.
The replaced text shall be copied into buffer, if specified, and
into the unnamed buffer. If the text to be replaced contains
characters from more than a single line, or the buffer text is in
line mode, the replaced text shall be copied into the numeric
buffers as well.
If the buffer text is in line mode:
1. Any lines that contain characters in the region shall be
deleted, and the editor shall enter text input mode at the
beginning of a new line which shall replace the first line
deleted.
2. If the autoindent edit option is set, autoindent characters
equal to the autoindent characters on the first line deleted
shall be inserted as if entered by the user.
Otherwise, if characters from more than one line are in the
region of text:
1. The text shall be deleted.
2. Any text remaining in the last line in the text region shall
be appended to the first line in the region, and the last
line in the region shall be deleted.
3. The editor shall enter text input mode after the last
character not deleted from the first line in the text region,
if any; otherwise, on the first column of the first line in
the region.
Otherwise:
1. If the glyph for '$' is smaller than the region, the end of
the region shall be marked with a '$'.
2. The editor shall enter text input mode, overwriting the
region of text.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Change to End-of-Line
Synopsis:
[buffer][count] C
This command shall be equivalent to the vi command:
[buffer][count] c$
See the c command.
Delete
Synopsis:
[buffer][count] d motion
If the motion command is the d command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count -1 lines after the current line
in the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count -1 lines.
Otherwise, the buffer text mode and text region shall be as
specified by the motion command.
If in open mode, and the current line is deleted, and the line
remains on the display, an '@' character shall be displayed as
the first glyph of that line.
Delete the region of text into buffer, if specified, and into the
unnamed buffer. If the text to be deleted contains characters
from more than a single line, or the buffer text is in line mode,
the deleted text shall be copied into the numeric buffers, as
well.
Current line: Set to the first text region line that appears in
the edit buffer, unless that line has been deleted, in which case
it shall be set to the last line in the edit buffer, or line 1 if
the edit buffer is empty.
Current column:
1. If the line is empty, set to column position 1.
2. Otherwise, if the buffer text is in line mode or the motion
was from the cursor toward the end of the edit buffer:
a. If a character from the current line is displayed in the
current column, set to the last column that displays any
portion of that character.
b. Otherwise, set to the last column in which any portion of
any character in the line is displayed.
3. Otherwise, if a character is displayed in the column that
began the text region, set to the last column that displays
any portion of that character.
4. Otherwise, set to the last column in which any portion of any
character in the line is displayed.
Delete to End-of-Line
Synopsis:
[buffer] D
Delete the text from the current position to the end of the
current line; equivalent to the vi command:
[buffer] d$
Move to End-of-Word
Synopsis:
[count] e
With the exception that words are used instead of bigwords as the
delimiter, this command shall be equivalent to the E command.
Move to End-of-Bigword
Synopsis:
[count] E
If the edit buffer is empty it shall be an error. If less than
count bigwords end between the cursor and the end of the edit
buffer, count shall be adjusted to the number of bigword endings
between the cursor and the end of the edit buffer.
If used as a motion command:
1. The text region shall be from the last character of the
countth next bigword up to and including the cursor
character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the
last character of the countth next bigword is displayed.
Find Character in Current Line (Forward)
Synopsis:
[count] f character
It shall be an error if count occurrences of the character do not
occur after the cursor in the line.
If used as a motion command:
1. The text range shall be from the cursor character up to and
including the countth occurrence of the specified character
after the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of
the countth occurrence of the specified character after the
cursor appears in the line.
Find Character in Current Line (Reverse)
Synopsis:
[count] F character
It shall be an error if count occurrences of the character do not
occur before the cursor in the line.
If used as a motion command:
1. The text region shall be from the countth occurrence of the
specified character before the cursor, up to, but not
including the cursor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of
the countth occurrence of the specified character before the
cursor appears in the line.
Move to Line
Synopsis:
[count] G
If count is not specified, it shall default to the last line of
the edit buffer. If count is greater than the last line of the
edit buffer, it shall be an error.
If used as a motion command:
1. The text region shall be from the cursor line up to and
including the specified line.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to count if count is specified; otherwise, the
last line.
Current column: Set to non-<blank>.
Move to Top of Screen
Synopsis:
[count] H
If the beginning of the line count greater than the first line of
which any portion appears on the display does not exist, it shall
be an error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall be from the starting line up
to and including (the first line of the display + count -1).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as
follows.
Current line: Set to (the first line of the display + count -1).
Current column: Set to non-<blank>.
Insert Before Cursor
Synopsis:
[count] i
Enter text input mode before the current cursor position. No
characters already in the edit buffer shall be affected by this
command. A count shall cause the input text to be appended count
-1 more times to the end of the input.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Insert at Beginning of Line
Synopsis:
[count] I
This command shall be equivalent to the vi command ^[count]i.
Join
Synopsis:
[count] J
If the current line is the last line in the edit buffer, it shall
be an error.
This command shall be equivalent to the ex join command with no
addresses, and an ex command count value of 1 if count was not
specified or if a count of 1 was specified, and an ex command
count value of count -1 for any other value of count, except that
the current line and column shall be set as follows.
Current line: Unchanged.
Current column: The last column in which any portion of the
character following the last character in the initial line is
displayed, or the last non-<newline> in the line if no characters
were appended.
Move to Bottom of Screen
Synopsis:
[count] L
If the beginning of the line count less than the last line of
which any portion appears on the display does not exist, it shall
be an error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the
starting cursor line to (the last line of the display -(count
-1)).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
1. If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
2. Otherwise, it shall set the current line and current column
as follows.
Current line: Set to (the last line of the display -(count -1)).
Current column: Set to non-<blank>.
Mark Position
Synopsis:
m letter
This command shall be equivalent to the ex mark command with the
specified character as an argument.
Move to Middle of Screen
Synopsis:
M
The middle line of the display shall be calculated as follows:
(the top line of the display) + (((number of lines displayed) +1) /2) -1
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the
starting cursor line up to and including the middle line of
the display.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as
follows.
Current line: Set to the middle line of the display.
Current column: Set to non-<blank>.
Repeat Regular Expression Find (Forward)
Synopsis:
n
If the remembered search direction was forward, the n command
shall be equivalent to the vi / command with no characters
entered by the user. Otherwise, it shall be equivalent to the vi
? command with no characters entered by the user.
If the n command is used as a motion command for the ! command,
the editor shall not enter text input mode on the last line on
the screen, and shall behave as if the user entered a single '!'
character as the text input.
Repeat Regular Expression Find (Reverse)
Synopsis:
N
Scan for the next match of the last pattern given to / or ?, but
in the reverse direction; this is the reverse of n.
If the remembered search direction was forward, the N command
shall be equivalent to the vi ? command with no characters
entered by the user. Otherwise, it shall be equivalent to the vi
/ command with no characters entered by the user. If the N
command is used as a motion command for the ! command, the
editor shall not enter text input mode on the last line on the
screen, and shall behave as if the user entered a single !
character as the text input.
Insert Empty Line Below
Synopsis:
o
Enter text input mode in a new line appended after the current
line. A count shall cause the input text to be appended count -1
more times to the end of the already added text, each time
starting on a new, appended line.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Insert Empty Line Above
Synopsis:
O
Enter text input mode in a new line inserted before the current
line. A count shall cause the input text to be appended count -1
more times to the end of the already added text, each time
starting on a new, appended line.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Put from Buffer Following
Synopsis:
[buffer] p
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be appended
below the current line, and each line of the buffer shall become
a new line in the edit buffer. A count shall cause the buffer
text to be appended count -1 more times to the end of the already
added text, each time starting on a new, appended line.
If the buffer text is in character mode, the text shall be
appended into the current line after the cursor, and each line of
the buffer other than the first and last shall become a new line
in the edit buffer. A count shall cause the buffer text to be
appended count -1 more times to the end of the already added
text, each time starting after the last added character.
Current line: If the buffer text is in line mode, set the line to
line +1; otherwise, unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer,
set to the last column on which any portion of the first
non-<blank> in the line is displayed.
2. If there is no non-<blank> in the first line of the buffer,
set to the last column on which any portion of the last
non-<newline> in the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line,
then set to the last column on which any portion of the first
character from the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the
last column on which any portion of the last character from
the buffer is displayed.
3. Otherwise, set to the first column on which any portion of
the first character from the buffer is displayed.
Put from Buffer Before
Synopsis:
[buffer] P
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be inserted
above the current line, and each line of the buffer shall become
a new line in the edit buffer. A count shall cause the buffer
text to be appended count -1 more times to the end of the already
added text, each time starting on a new, appended line.
If the buffer text is in character mode, the text shall be
inserted into the current line before the cursor, and each line
of the buffer other than the first and last shall become a new
line in the edit buffer. A count shall cause the buffer text to
be appended count -1 more times to the end of the already added
text, each time starting after the last added character.
Current line: Unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer,
set to the last column on which any portion of that character
is displayed.
2. If there is no non-<blank> in the first line of the buffer,
set to the last column on which any portion of the last
non-<newline> in the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line,
then set to the last column on which any portion of the first
character from the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the
last column on which any portion of the last character from
the buffer is displayed.
3. Otherwise, set to the first column on which any portion of
the first character from the buffer is displayed.
Enter ex Mode
Synopsis:
Q
Leave visual or open mode and enter ex command mode.
Current line: Unchanged.
Current column: Unchanged.
Replace Character
Synopsis:
[count] r character
Replace the count characters at and after the cursor with the
specified character. If there are less than count non-<newline>
characters at and after the cursor on the line, it shall be an
error.
If character is <control>‐V, any next character other than the
<newline> shall be stripped of any special meaning and used as a
literal character.
If character is <ESC>, no replacement shall be made and the
current line and current column shall be unchanged.
If character is <carriage-return> or <newline>, count new lines
shall be appended to the current line. All but the last of these
lines shall be empty. count characters at and after the cursor
shall be discarded, and any remaining characters after the cursor
in the current line shall be moved to the last of the new lines.
If the autoindent edit option is set, they shall be preceded by
the same number of autoindent characters found on the line from
which the command was executed.
Current line: Unchanged unless the replacement character is a
<carriage-return> or <newline>, in which case it shall be set to
line + count.
Current column: Set to the last column position on which a
portion of the last replaced character is displayed, or if the
replacement character caused new lines to be created, set to
non-<blank>.
Replace Characters
Synopsis:
R
Enter text input mode at the current cursor position possibly
replacing text on the current line. A count shall cause the input
text to be appended count -1 more times to the end of the input.
Current line/column: As specified for the text input commands
(see Input Mode Commands in vi).
Substitute Character
Synopsis:
[buffer][count] s
This command shall be equivalent to the vi command:
[buffer][count] c<space>
Substitute Lines
Synopsis:
[buffer][count] S
This command shall be equivalent to the vi command:
[buffer][count] c_
Move Cursor to Before Character (Forward)
Synopsis:
[count] t character
It shall be an error if count occurrences of the character do not
occur after the cursor in the line.
If used as a motion command:
1. The text region shall be from the cursor up to but not
including the countth occurrence of the specified character
after the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of
the character before the countth occurrence of the specified
character after the cursor appears in the line.
Move Cursor to After Character (Reverse)
Synopsis:
[count] T character
It shall be an error if count occurrences of the character do not
occur before the cursor in the line.
If used as a motion command:
1. If the character before the cursor is the specified
character, it shall be an error.
2. The text region shall be from the character before the cursor
up to but not including the countth occurrence of the
specified character before the cursor.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of
the character after the countth occurrence of the specified
character before the cursor appears in the line.
Undo
Synopsis:
u
This command shall be equivalent to the ex undo command except
that the current line and current column shall be set as follows:
Current line: Set to the first line added or changed if any;
otherwise, move to the line preceding any deleted text if one
exists; otherwise, move to line 1.
Current column: If undoing an ex command, set to the first
non-<blank>.
Otherwise, if undoing a text input command:
1. If the command was a C, c, O, o, R, S, or s command, the
current column shall be set to the value it held when the
text input command was entered.
2. Otherwise, set to the last column in which any portion of the
first character after the deleted text is displayed, or, if
no non-<newline> characters follow the text deleted from this
line, set to the last column in which any portion of the last
non-<newline> in the line is displayed, or 1 if the line is
empty.
Otherwise, if a single line was modified (that is, not added or
deleted) by the u command:
1. If text was added or changed, set to the last column in which
any portion of the first character added or changed is
displayed.
2. If text was deleted, set to the last column in which any
portion of the first character after the deleted text is
displayed, or, if no non-<newline> characters follow the
deleted text, set to the last column in which any portion of
the last non-<newline> in the line is displayed, or 1 if the
line is empty.
Otherwise, set to non-<blank>.
Undo Current Line
Synopsis:
U
Restore the current line to its state immediately before the most
recent time that it became the current line.
Current line: Unchanged.
Current column: Set to the first column in the line in which any
portion of the first character in the line is displayed.
Move to Beginning of Word
Synopsis:
[count] w
With the exception that words are used as the delimiter instead
of bigwords, this command shall be equivalent to the W command.
Move to Beginning of Bigword
Synopsis:
[count] W
If the edit buffer is empty, it shall be an error. If there are
less than count bigwords between the cursor and the end of the
edit buffer, count shall be adjusted to move the cursor to the
last bigword in the edit buffer.
If used as a motion command:
1. If the associated command is c, count is 1, and the cursor is
on a <blank>, the region of text shall be the current
character and no further action shall be taken.
2. If there are less than count bigwords between the cursor and
the end of the edit buffer, then the command shall succeed,
and the region of text shall include the last character of
the edit buffer.
3. If there are <blank> characters or an end-of-line that
precede the countth bigword, and the associated command is c,
the region of text shall be up to and including the last
character before the preceding <blank> characters or end-of-
line.
4. If there are <blank> characters or an end-of-line that
precede the bigword, and the associated command is d or y,
the region of text shall be up to and including the last
<blank> before the start of the bigword or end-of-line.
5. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
1. If the cursor is on the last character of the edit buffer, it
shall be an error.
Current line: Set to the line containing the current column.
Current column: Set to the last column in which any part of the
first character of the countth next bigword is displayed.
Delete Character at Cursor
Synopsis:
[buffer][count] x
Delete the count characters at and after the current character
into buffer, if specified, and into the unnamed buffer.
If the line is empty, it shall be an error. If there are less
than count non-<newline> characters at and after the cursor on
the current line, count shall be adjusted to the number of
non-<newline> characters at and after the cursor.
Current line: Unchanged.
Current column: If the line is empty, set to column position 1.
Otherwise, if there were count or less non-<newline> characters
at and after the cursor on the current line, set to the last
column that displays any part of the last non-<newline> of the
line. Otherwise, unchanged.
Delete Character Before Cursor
Synopsis:
[buffer][count] X
Delete the count characters before the current character into
buffer, if specified, and into the unnamed buffer.
If there are no characters before the current character on the
current line, it shall be an error. If there are less than count
previous characters on the current line, count shall be adjusted
to the number of previous characters on the line.
Current line: Unchanged.
Current column: Set to (current column - the width of the deleted
characters).
Yank
Synopsis:
[buffer][count] y motion
Copy (yank) the region of text into buffer, if specified, and
into the unnamed buffer.
If the motion command is the y command repeated:
1. The buffer shall be in line mode.
2. If there are less than count -1 lines after the current line
in the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count -1 lines.
Otherwise, the buffer text mode and text region shall be as
specified by the motion command.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to
the first line in the edit buffer that is part of the text region
specified by the motion command.
Current column:
1. If the motion was from the current cursor position toward the
end of the edit buffer, unchanged.
2. Otherwise, if the current line is empty, set to column
position 1.
3. Otherwise, set to the last column that displays any part of
the first character in the file that is part of the text
region specified by the motion command.
Yank Current Line
Synopsis:
[buffer][count] Y
This command shall be equivalent to the vi command:
[buffer][count] y_
Redraw Window
If in open mode, the z command shall have the Synopsis:
Synopsis:
[count] z
If count is not specified, it shall default to the window edit
option -1. The z command shall be equivalent to the ex z command,
with a type character of = and a count of count -2, except that
the current line and current column shall be set as follows, and
the window edit option shall not be affected. If the calculation
for the count argument would result in a negative number, the
count argument to the ex z command shall be zero. A blank line
shall be written after the last line is written.
Current line: Unchanged.
Current column: Unchanged.
If not in open mode, the z command shall have the following
Synopsis:
Synopsis:
[line] z [count] character
If line is not specified, it shall default to the current line.
If line is specified, but is greater than the number of lines in
the edit buffer, it shall default to the number of lines in the
edit buffer.
If count is specified, the value of the window edit option shall
be set to count (as described in the ex window command), and the
screen shall be redrawn.
line shall be placed as specified by the following characters:
<newline>, <carriage-return>
Place the beginning of the line on the first line of the
display.
. Place the beginning of the line in the center of the
display. The middle line of the display shall be calculated
as described for the M command.
- Place an unspecified portion of the line on the last line
of the display.
+ If line was specified, equivalent to the <newline> case. If
line was not specified, display a screen where the first
line of the display shall be (current last line) +1. If
there are no lines after the last line in the display, it
shall be an error.
^ If line was specified, display a screen where the last line
of the display shall contain an unspecified portion of the
first line of a display that had an unspecified portion of
the specified line on the last line of the display. If this
calculation results in a line before the beginning of the
edit buffer, display the first screen of the edit buffer.
Otherwise, display a screen where the last line of the
display shall contain an unspecified portion of (current
first line -1). If this calculation results in a line
before the beginning of the edit buffer, it shall be an
error.
Current line: If line and the '^' character were specified:
1. If the first screen was displayed as a result of the command
attempting to display lines before the beginning of the edit
buffer: if the first screen was already displayed, unchanged;
otherwise, set to (current first line -1).
2. Otherwise, set to the last line of the display.
If line and the '+' character were specified, set to the first
line of the display.
Otherwise, if line was specified, set to line.
Otherwise, unchanged.
Current column: Set to non-<blank>.
Exit
Synopsis:
ZZ
This command shall be equivalent to the ex xit command with no
addresses, trailing !, or filename (see the ex xit command).
Input Mode Commands in vi
In text input mode, the current line shall consist of zero or
more of the following categories, plus the terminating <newline>:
1. Characters preceding the text input entry point
Characters in this category shall not be modified during text
input mode.
2. autoindent characters
autoindent characters shall be automatically inserted into
each line that is created in text input mode, either as a
result of entering a <newline> or <carriage-return> while in
text input mode, or as an effect of the command itself; for
example, O or o (see the ex autoindent command), as if
entered by the user.
It shall be possible to erase autoindent characters with the
<control>‐D command; it is unspecified whether they can be
erased by <control>‐H, <control>‐U, and <control>‐W
characters. Erasing any autoindent character turns the glyph
into erase-columns and deletes the character from the edit
buffer, but does not change its representation on the screen.
3. Text input characters
Text input characters are the characters entered by the user.
Erasing any text input character turns the glyph into erase-
columns and deletes the character from the edit buffer, but
does not change its representation on the screen.
Each text input character entered by the user (that does not
have a special meaning) shall be treated as follows:
a. The text input character shall be appended to the last
character in the edit buffer from the first, second, or
third categories.
b. If there are no erase-columns on the screen, the text
input command was the R command, and characters in the
fifth category from the original line follow the cursor,
the next such character shall be deleted from the edit
buffer. If the slowopen edit option is not set, the
corresponding glyph on the screen shall become erase-
columns.
c. If there are erase-columns on the screen, as many columns
as they occupy, or as are necessary, shall be overwritten
to display the text input character. (If only part of a
multi-column glyph is overwritten, the remainder shall be
left on the screen, and continue to be treated as erase-
columns; it is unspecified whether the remainder of the
glyph is modified in any way.)
d. If additional display line columns are needed to display
the text input character:
i. If the slowopen edit option is set, the text input
characters shall be displayed on subsequent display
line columns, overwriting any characters displayed
in those columns.
ii. Otherwise, any characters currently displayed on or
after the column on the display line where the text
input character is to be displayed shall be pushed
ahead the number of display line columns necessary
to display the rest of the text input character.
4. Erase-columns
Erase-columns are not logically part of the edit buffer,
appearing only on the screen, and may be overwritten on the
screen by subsequent text input characters. When text input
mode ends, all erase-columns shall no longer appear on the
screen.
Erase-columns are initially the region of text specified by
the c command (see Change); however, erasing autoindent or
text input characters causes the glyphs of the erased
characters to be treated as erase-columns.
5. Characters following the text region for the c command, or
the text input entry point for all other commands
Characters in this category shall not be modified during text
input mode, except as specified in category 3.b. for the R
text input command, or as <blank> characters deleted when a
<newline> or <carriage-return> is entered.
It is unspecified whether it is an error to attempt to erase past
the beginning of a line that was created by the entry of a
<newline> or <carriage-return> during text input mode. If it is
not an error, the editor shall behave as if the erasing character
was entered immediately after the last text input character
entered on the previous line, and all of the non-<newline>
characters on the current line shall be treated as erase-columns.
When text input mode is entered, or after a text input mode
character is entered (except as specified for the special
characters below), the cursor shall be positioned as follows:
1. On the first column that displays any part of the first
erase-column, if one exists
2. Otherwise, if the slowopen edit option is set, on the first
display line column after the last character in the first,
second, or third categories, if one exists
3. Otherwise, the first column that displays any part of the
first character in the fifth category, if one exists
4. Otherwise, the display line column after the last character
in the first, second, or third categories, if one exists
5. Otherwise, on column position 1
The characters that are updated on the screen during text input
mode are unspecified, other than that the last text input
character shall always be updated, and, if the slowopen edit
option is not set, the current cursor character shall always be
updated.
The following specifications are for command characters entered
during text input mode.
NUL
Synopsis:
NUL
If the first character of the text input is a NUL, the most
recently input text shall be input as if entered by the user, and
then text input mode shall be exited. The text shall be input
literally; that is, characters are neither macro or abbreviation
expanded, nor are any characters interpreted in any special
manner. It is unspecified whether implementations shall support
more than 256 bytes of remembered input text.
<control>-D
Synopsis:
<control>-D
The <control>‐D character shall have no special meaning when in
text input mode for a line-oriented command (see Command
Descriptions in vi).
This command need not be supported on block-mode terminals.
If the cursor does not follow an autoindent character, or an
autoindent character and a '0' or '^' character:
1. If the cursor is in column position 1, the <control>‐D
character shall be discarded and no further action taken.
2. Otherwise, the <control>‐D character shall have no special
meaning.
If the last input character was a '0', the cursor shall be moved
to column position 1.
Otherwise, if the last input character was a '^', the cursor
shall be moved to column position 1. In addition, the autoindent
level for the next input line shall be derived from the same line
from which the autoindent level for the current input line was
derived.
Otherwise, the cursor shall be moved back to the column after the
previous shiftwidth (see the ex shiftwidth command) boundary.
All of the glyphs on columns between the starting cursor position
and (inclusively) the ending cursor position shall become erase-
columns as described in Input Mode Commands in vi.
Current line: Unchanged.
Current column: Set to 1 if the <control>‐D was preceded by a '^'
or '0'; otherwise, set to (column -1) -((column -2) %
shiftwidth).
<control>-H
Synopsis:
<control>-H
If in text input mode for a line-oriented command, and there are
no characters to erase, text input mode shall be terminated, no
further action shall be done for this command, and the current
line and column shall be unchanged.
If there are characters other than autoindent characters that
have been input on the current line before the cursor, the cursor
shall move back one character.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐H command is an error or if the cursor moves back one
autoindent character.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐H command is an error or if it is
equivalent to entering <control>‐H after the last input character
on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position
and (inclusively) the ending cursor position shall become erase-
columns as described in Input Mode Commands in vi.
The current erase character (see stty) shall cause an equivalent
action to the <control>‐H command, unless the previously inserted
character was a <backslash>, in which case it shall be as if the
literal current erase character had been inserted instead of the
<backslash>.
Current line: Unchanged, unless previously input lines are
erased, in which case it shall be set to line -1.
Current column: Set to the first column that displays any portion
of the character backed up over.
<newline>
Synopsis:
<newline>
<carriage-return>
<control>-J
<control>-M
If input was part of a line-oriented command, text input mode
shall be terminated and the command shall continue execution with
the input provided.
Otherwise, terminate the current line. If there are no characters
other than autoindent characters on the line, all characters on
the line shall be discarded. Otherwise, it is unspecified
whether the autoindent characters in the line are modified by
entering these characters.
Continue text input mode on a new line appended after the current
line. If the slowopen edit option is set, the lines on the
screen below the current line shall not be pushed down, but the
first of them shall be cleared and shall appear to be
overwritten. Otherwise, the lines of the screen below the current
line shall be pushed down.
If the autoindent edit option is set, an appropriate number of
autoindent characters shall be added as a prefix to the line as
described by the ex autoindent edit option.
All columns after the cursor that are erase-columns (as described
in Input Mode Commands in vi) shall be discarded.
If the autoindent edit option is set, all <blank> characters
immediately following the cursor shall be discarded.
All remaining characters after the cursor shall be transferred to
the new line, positioned after any autoindent characters.
Current line: Set to current line +1.
Current column: Set to the first column that displays any portion
of the first character after the autoindent characters on the new
line, if any, or the first column position after the last
autoindent character, if any, or column position 1.
<control>-T
Synopsis:
<control>-T
The <control>‐T character shall have no special meaning when in
text input mode for a line-oriented command (see Command
Descriptions in vi).
This command need not be supported on block-mode terminals.
Behave as if the user entered the minimum number of <blank>
characters necessary to move the cursor forward to the column
position after the next shiftwidth (see the ex shiftwidth
command) boundary.
Current line: Unchanged.
Current column: Set to column + shiftwidth - ((column -1) %
shiftwidth).
<control>-U
Synopsis:
<control>-U
If there are characters other than autoindent characters that
have been input on the current line before the cursor, the cursor
shall move to the first character input after the autoindent
characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐U command is an error or if the cursor moves to the
first column position on the line.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐U command is an error or if it is
equivalent to entering <control>‐U after the last input character
on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position
and (inclusively) the ending cursor position shall become erase-
columns as described in Input Mode Commands in vi.
The current kill character (see stty) shall cause an equivalent
action to the <control>‐U command, unless the previously inserted
character was a <backslash>, in which case it shall be as if the
literal current kill character had been inserted instead of the
<backslash>.
Current line: Unchanged, unless previously input lines are
erased, in which case it shall be set to line -1.
Current column: Set to the first column that displays any portion
of the last character backed up over.
<control>-V
Synopsis:
<control>-V
<control>-Q
Allow the entry of any subsequent character, other than
<control>‐J or the <newline>, as a literal character, removing
any special meaning that it may have to the editor in text input
mode. If a <control>‐V or <control>‐Q is entered before a
<control>‐J or <newline>, the <control>‐V or <control>‐Q
character shall be discarded, and the <control>‐J or <newline>
shall behave as described in the <newline> command character
during input mode.
For purposes of the display only, the editor shall behave as if a
'^' character was entered, and the cursor shall be positioned as
if overwriting the '^' character. When a subsequent character is
entered, the editor shall behave as if that character was entered
instead of the original <control>‐V or <control>‐Q character.
Current line: Unchanged.
Current column: Unchanged.
<control>-W
Synopsis:
<control>-W
If there are characters other than autoindent characters that
have been input on the current line before the cursor, the cursor
shall move back over the last word preceding the cursor
(including any <blank> characters between the end of the last
word and the current cursor); the cursor shall not move to before
the first character after the end of any autoindent characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐W command is an error or if the cursor moves to the
first column position on the line.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐W command is an error or if it is
equivalent to entering <control>‐W after the last input character
on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position
and (inclusively) the ending cursor position shall become erase-
columns as described in Input Mode Commands in vi.
Current line: Unchanged, unless previously input lines are
erased, in which case it shall be set to line -1.
Current column: Set to the first column that displays any portion
of the last character backed up over.
<ESC>
Synopsis:
<ESC>
If input was part of a line-oriented command:
1. If interrupt was entered, text input mode shall be terminated
and the editor shall return to command mode. The terminal
shall be alerted.
2. If <ESC> was entered, text input mode shall be terminated and
the command shall continue execution with the input provided.
Otherwise, terminate text input mode and return to command mode.
Any autoindent characters entered on newly created lines that
have no other non-<newline> characters shall be deleted.
Any leading autoindent and <blank> characters on newly created
lines shall be rewritten to be the minimum number of <blank>
characters possible.
The screen shall be redisplayed as necessary to match the
contents of the edit buffer.
Current line: Unchanged.
Current column:
1. If there are text input characters on the current line, the
column shall be set to the last column where any portion of
the last text input character is displayed.
2. Otherwise, if a character is displayed in the current column,
unchanged.
3. Otherwise, set to column position 1.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
When any error is encountered and the standard input is not a
terminal device file, vi shall not write the file or return to
command or text input mode, and shall terminate with a non-zero
exit status.
Otherwise, when an unrecoverable error is encountered it shall be
equivalent to a SIGHUP asynchronous event.
Otherwise, when an error is encountered, the editor shall behave
as specified in Command Descriptions in vi.
The following sections are informative.
None.
None.
See the RATIONALE for ex(1p) for more information on vi. Major
portions of the vi utility specification point to ex to avoid
inadvertent divergence. While ex and vi have historically been
implemented as a single utility, this is not required by
POSIX.1‐2008.
It is recognized that portions of vi would be difficult, if not
impossible, to implement satisfactorily on a block-mode terminal,
or a terminal without any form of cursor addressing, thus it is
not a mandatory requirement that such features should work on all
terminals. It is the intention, however, that a vi implementation
should provide the full set of capabilities on all terminals
capable of supporting them.
Historically, vi exited immediately if the standard input was not
a terminal. POSIX.1‐2008 permits, but does not require, this
behavior. An end-of-file condition is not equivalent to an end-
of-file character. A common end-of-file character, <control>‐D,
is historically a vi command.
The text in the STDOUT section reflects the usage of the verb
display in this section; some implementations of vi use standard
output to write to the terminal, but POSIX.1‐2008 does not
require that to be the case.
Historically, implementations reverted to open mode if the
terminal was incapable of supporting full visual mode.
POSIX.1‐2008 requires this behavior. Historically, the open mode
of vi behaved roughly equivalently to the visual mode, with the
exception that only a single line from the edit buffer (one
``buffer line'') was kept current at any time. This line was
normally displayed on the next-to-last line of a terminal with
cursor addressing (and the last line performed its normal visual
functions for line-oriented commands and messages). In addition,
some few commands behaved differently in open mode than in visual
mode. POSIX.1‐2008 requires conformance to historical practice.
Historically, ex and vi implementations have expected text to
proceed in the usual European/Latin order of left to right, top
to bottom. There is no requirement in POSIX.1‐2008 that this be
the case. The specification was deliberately written using words
like ``before'', ``after'', ``first'', and ``last'' in order to
permit implementations to support the natural text order of the
language.
Historically, lines past the end of the edit buffer were marked
with single <tilde> ('~') characters; that is, if the one-based
display was 20 lines in length, and the last line of the file was
on line one, then lines 2-20 would contain only a single '~'
character.
Historically, the vi editor attempted to display only complete
lines at the bottom of the screen (it did display partial lines
at the top of the screen). If a line was too long to fit in its
entirety at the bottom of the screen, the screen lines where the
line would have been displayed were displayed as single '@'
characters, instead of displaying part of the line. POSIX.1‐2008
permits, but does not require, this behavior. Implementations are
encouraged to attempt always to display a complete line at the
bottom of the screen when doing scrolling or screen positioning
by buffer lines.
Historically, lines marked with '@' were also used to minimize
output to dumb terminals over slow lines; that is, changes local
to the cursor were updated, but changes to lines on the screen
that were not close to the cursor were simply marked with an '@'
sign instead of being updated to match the current text.
POSIX.1‐2008 permits, but does not require this feature because
it is used ever less frequently as terminals become smarter and
connections are faster.
Initialization in ex and vi
Historically, vi always had a line in the edit buffer, even if
the edit buffer was ``empty''. For example:
1. The ex command = executed from visual mode wrote ``1'' when
the buffer was empty.
2. Writes from visual mode of an empty edit buffer wrote files
of a single character (a <newline>), while writes from ex
mode of an empty edit buffer wrote empty files.
3. Put and read commands into an empty edit buffer left an empty
line at the top of the edit buffer.
For consistency, POSIX.1‐2008 does not permit any of these
behaviors.
Historically, vi did not always return the terminal to its
original modes; for example, ICRNL was modified if it was not
originally set. POSIX.1‐2008 does not permit this behavior.
Command Descriptions in vi
Motion commands are among the most complicated aspects of vi to
describe. With some exceptions, the text region and buffer type
effect of a motion command on a vi command are described on a
case-by-case basis. The descriptions of text regions in
POSIX.1‐2008 are not intended to imply direction; that is, an
inclusive region from line n to line n+5 is identical to a region
from line n+5 to line n. This is of more than academic interest—
movements to marks can be in either direction, and, if the
wrapscan option is set, so can movements to search points.
Historically, lines are always stored into buffers in text order;
that is, from the start of the edit buffer to the end.
POSIX.1‐2008 requires conformance to historical practice.
Historically, command counts were applied to any associated
motion, and were multiplicative to any supplied motion count. For
example, 2cw is the same as c2w, and 2c3w is the same as c6w.
POSIX.1‐2008 requires this behavior. Historically, vi commands
that used bigwords, words, paragraphs, and sentences as objects
treated groups of empty lines, or lines that contained only
<blank> characters, inconsistently. Some commands treated them as
a single entity, while others treated each line separately. For
example, the w, W, and B commands treated groups of empty lines
as individual words; that is, the command would move the cursor
to each new empty line. The e and E commands treated groups of
empty lines as a single word; that is, the first use would move
past the group of lines. The b command would just beep at the
user, or if done from the start of the line as a motion command,
fail in unexpected ways. If the lines contained only (or ended
with) <blank> characters, the w and W commands would just beep at
the user, the E and e commands would treat the group as a single
word, and the B and b commands would treat the lines as
individual words. For consistency and simplicity of
specification, POSIX.1‐2008 requires that all vi commands treat
groups of empty or blank lines as a single entity, and that
movement through lines ending with <blank> characters be
consistent with other movements.
Historically, vi documentation indicated that any number of
double-quotes were skipped after punctuation marks at sentence
boundaries; however, implementations only skipped single-quotes.
POSIX.1‐2008 requires both to be skipped.
Historically, the first and last characters in the edit buffer
were word boundaries. This historical practice is required by
POSIX.1‐2008.
Historically, vi attempted to update the minimum number of
columns on the screen possible, which could lead to misleading
information being displayed. POSIX.1‐2008 makes no requirements
other than that the current character being entered is displayed
correctly, leaving all other decisions in this area up to the
implementation.
Historically, lines were arbitrarily folded between columns of
any characters that required multiple column positions on the
screen, with the exception of tabs, which terminated at the
right-hand margin. POSIX.1‐2008 permits the former and requires
the latter. Implementations that do not arbitrarily break lines
between columns of characters that occupy multiple column
positions should not permit the cursor to rest on a column that
does not contain any part of a character.
The historical vi had a problem in that all movements were by
buffer lines, not by display or screen lines. This is often the
right thing to do; for example, single line movements, such as j
or k, should work on buffer lines. Commands like dj, or j., where
. is a change command, only make sense for buffer lines. It is
not, however, the right thing to do for screen motion or
scrolling commands like <control>‐D, <control>‐F, and H. If the
window is fairly small, using buffer lines in these cases can
result in completely random motion; for example, 1<control>‐D can
result in a completely changed screen, without any overlap. This
is clearly not what the user wanted. The problem is even worse in
the case of the H, L, and M commands—as they position the cursor
at the first non-<blank> of the line, they may all refer to the
same location in large lines, and will result in no movement at
all.
In addition, if the line is larger than the screen, using buffer
lines can make it impossible to display parts of the line—there
are not any commands that do not display the beginning of the
line in historical vi, and if both the beginning and end of the
line cannot be on the screen at the same time, the user suffers.
Finally, the page and half-page scrolling commands historically
moved to the first non-<blank> in the new line. If the line is
approximately the same size as the screen, this is inadequate
because the cursor before and after a <control>‐D command will
refer to the same location on the screen.
Implementations of ex and vi exist that do not have these
problems because the relevant commands (<control>‐B, <control>‐D,
<control>‐F, <control>‐U, <control>‐Y, <control>‐E, H, L, and M)
operate on display (screen) lines, not (edit) buffer lines.
POSIX.1‐2008 does not permit this behavior by default because the
standard developers believed that users would find it too
confusing. However, historical practice has been relaxed. For
example, ex and vi historically attempted, albeit sometimes
unsuccessfully, to never put part of a line on the last lines of
a screen; for example, if a line would not fit in its entirety,
no part of the line was displayed, and the screen lines
corresponding to the line contained single '@' characters. This
behavior is permitted, but not required by POSIX.1‐2008, so that
it is possible for implementations to support long lines in small
screens more reasonably without changing the commands to be
oriented to the display (instead of oriented to the buffer).
POSIX.1‐2008 also permits implementations to refuse to edit any
edit buffer containing a line that will not fit on the screen in
its entirety.
The display area (for example, the value of the window edit
option) has historically been ``grown'', or expanded, to display
new text when local movements are done in displays where the
number of lines displayed is less than the maximum possible.
Expansion has historically been the first choice, when the target
line is less than the maximum possible expansion value away.
Scrolling has historically been the next choice, done when the
target line is less than half a display away, and otherwise, the
screen was redrawn. There were exceptions, however, in that ex
commands generally always caused the screen to be redrawn.
POSIX.1‐2008 does not specify a standard behavior because there
may be external issues, such as connection speed, the number of
characters necessary to redraw as opposed to scroll, or terminal
capabilities that implementations will have to accommodate.
The current line in POSIX.1‐2008 maps one-to-one to a buffer line
in the file. The current column does not. There are two different
column values that are described by POSIX.1‐2008. The first is
the current column value as set by many of the vi commands. This
value is remembered for the lifetime of the editor. The second
column value is the actual position on the screen where the
cursor rests. The two are not always the same. For example, when
the cursor is backed by a multi-column character, the actual
cursor position on the screen has historically been the last
column of the character in command mode, and the first column of
the character in input mode.
Commands that set the current line, but that do not set the
current cursor value (for example, j and k) attempt to get as
close as possible to the remembered column position, so that the
cursor tends to restrict itself to a vertical column as the user
moves around in the edit buffer. POSIX.1‐2008 requires
conformance to historical practice, requiring that the display
location of the cursor on the display line be adjusted from the
current column value as necessary to support this historical
behavior.
Historically, only a single line (and for some terminals, a
single line minus 1 column) of characters could be entered by the
user for the line-oriented commands; that is, :, !, /, or ?.
POSIX.1‐2008 permits, but does not require, this limitation.
Historically, ``soft'' errors in vi caused the terminal to be
alerted, but no error message was displayed. As a general rule,
no error message was displayed for errors in command execution in
vi, when the error resulted from the user attempting an invalid
or impossible action, or when a searched-for object was not
found. Examples of soft errors included h at the left margin,
<control>‐B or [[ at the beginning of the file, 2G at the end of
the file, and so on. In addition, errors such as %, ]], }, ), N,
n, f, F, t, and T failing to find the searched-for object were
soft as well. Less consistently, / and ? displayed an error
message if the pattern was not found, /, ?, N, and n displayed an
error message if no previous regular expression had been
specified, and ; did not display an error message if no previous
f, F, t, or T command had occurred. Also, behavior in this area
might reasonably be based on a runtime evaluation of the speed of
a network connection. Finally, some implementations have
provided error messages for soft errors in order to assist naive
users, based on the value of a verbose edit option. POSIX.1‐2008
does not list specific errors for which an error message shall be
displayed. Implementations should conform to historical practice
in the absence of any strong reason to diverge.
Page Backwards
The <control>‐B and <control>‐F commands historically considered
it an error to attempt to page past the beginning or end of the
file, whereas the <control>‐D and <control>‐U commands simply
moved to the beginning or end of the file. For consistency,
POSIX.1‐2008 requires the latter behavior for all four commands.
All four commands still consider it an error if the current line
is at the beginning (<control>‐B, <control>‐U) or end
(<control>‐F, <control>‐D) of the file. Historically, the
<control>‐B and <control>‐F commands skip two lines in order to
include overlapping lines when a single command is entered. This
makes less sense in the presence of a count, as there will be, by
definition, no overlapping lines. The actual calculation used by
historical implementations of the vi editor for <control>‐B was:
((current first line) - count x (window edit option)) +2
and for <control>‐F was:
((current first line) + count x (window edit option)) -2
This calculation does not work well when intermixing commands
with and without counts; for example, 3<control>‐F is not
equivalent to entering the <control>‐F command three times, and
is not reversible by entering the <control>‐B command three
times. For consistency with other vi commands that take counts,
POSIX.1‐2008 requires a different calculation.
Scroll Forward
The 4BSD and System V implementations of vi differed on the
initial value used by the scroll command. 4BSD used:
((window edit option) +1) /2
while System V used the value of the scroll edit option. The
System V version is specified by POSIX.1‐2008 because the
standard developers believed that it was more intuitive and
permitted the user a method of setting the scroll value initially
without also setting the number of lines that are displayed.
Scroll Forward by Line
Historically, the <control>‐E and <control>‐Y commands considered
it an error if the last and first lines, respectively, were
already on the screen. POSIX.1‐2008 requires conformance to
historical practice. Historically, the <control>‐E and
<control>‐Y commands had no effect in open mode. For simplicity
and consistency of specification, POSIX.1‐2008 requires that they
behave as usual, albeit with a single line screen.
Clear and Redisplay
The historical <control>‐L command refreshed the screen exactly
as it was supposed to be currently displayed, replacing any '@'
characters for lines that had been deleted but not updated on the
screen with refreshed '@' characters. The intent of the
<control>‐L command is to refresh when the screen has been
accidentally overwritten; for example, by a write command from
another user, or modem noise.
Redraw Screen
The historical <control>‐R command redisplayed only when
necessary to update lines that had been deleted but not updated
on the screen and that were flagged with '@' characters. There is
no requirement that the screen be in any way refreshed if no
lines of this form are currently displayed. POSIX.1‐2008 permits
implementations to extend this command to refresh lines on the
screen flagged with '@' characters because they are too long to
be displayed in the current framework; however, the current line
and column need not be modified.
Search for tagstring
Historically, the first non-<blank> at or after the cursor was
the first character, and all subsequent characters that were word
characters, up to the end of the line, were included. For
example, with the cursor on the leading <space> or on the '#'
character in the text "#bar@", the tag was "#bar". On the
character 'b' it was "bar", and on the 'a' it was "ar".
POSIX.1‐2008 requires this behavior.
Replace Text with Results from Shell Command
Historically, the <, >, and ! commands considered most cursor
motions other than line-oriented motions an error; for example,
the command >/foo<CR> succeeded, while the command >l failed,
even though the text region described by the two commands might
be identical. For consistency, all three commands only consider
entire lines and not partial lines, and the region is defined as
any line that contains a character that was specified by the
motion.
Move to Matching Character
Other matching characters have been left implementation-defined
in order to allow extensions such as matching '<' and '>' for
searching HTML, or #ifdef, #else, and #endif for searching C
source.
Repeat Substitution
POSIX.1‐2008 requires that any c and g flags specified to the
previous substitute command be ignored; however, the r flag may
still apply, if supported by the implementation.
Return to Previous (Context or Section)
The [[, ]], (, ), {, and } commands are all affected by ``section
boundaries'', but in some historical implementations not all of
the commands recognize the same section boundaries. This is a
bug, not a feature, and a unique section-boundary algorithm was
not described for each command. One special case that is
preserved is that the sentence command moves to the end of the
last line of the edit buffer while the other commands go to the
beginning, in order to preserve the traditional character cut
semantics of the sentence command. Historically, vi section
boundaries at the beginning and end of the edit buffer were the
first non-<blank> on the first and last lines of the edit buffer
if one exists; otherwise, the last character of the first and
last lines of the edit buffer if one exists. To increase
consistency with other section locations, this has been
simplified by POSIX.1‐2008 to the first character of the first
and last lines of the edit buffer, or the first and the last
lines of the edit buffer if they are empty.
Sentence boundaries were problematic in the historical vi. They
were not only the boundaries as defined for the section and
paragraph commands, but they were the first non-<blank> that
occurred after those boundaries, as well. Historically, the vi
section commands were documented as taking an optional window
size as a count preceding the command. This was not implemented
in historical versions, so POSIX.1‐2008 requires that the count
repeat the command, for consistency with other vi commands.
Repeat
Historically, mapped commands other than text input commands
could not be repeated using the period command. POSIX.1‐2008
requires conformance to historical practice.
The restrictions on the interpretation of special characters (for
example, <control>‐H) in the repetition of text input mode
commands is intended to match historical practice. For example,
given the input sequence:
iab<control>-H<control>-H<control>-Hdef<escape>
the user should be informed of an error when the sequence is
first entered, but not during a command repetition. The character
<control>‐T is specifically exempted from this restriction.
Historical implementations of vi ignored <control>‐T characters
that were input in the original command during command
repetition. POSIX.1‐2008 prohibits this behavior.
Find Regular Expression
Historically, commands did not affect the line searched to or
from if the motion command was a search (/, ?, N, n) and the
final position was the start/end of the line. There were some
special cases and vi was not consistent. POSIX.1‐2008 does not
permit this behavior, for consistency. Historical implementations
permitted but were unable to handle searches as motion commands
that wrapped (that is, due to the edit option wrapscan) to the
original location. POSIX.1‐2008 requires that this behavior be
treated as an error.
Historically, the syntax "/RE/0" was used to force the command to
cut text in line mode. POSIX.1‐2008 requires conformance to
historical practice.
Historically, in open mode, a z specified to a search command
redisplayed the current line instead of displaying the current
screen with the current line highlighted. For consistency and
simplicity of specification, POSIX.1‐2008 does not permit this
behavior.
Historically, trailing z commands were permitted and ignored if
entered as part of a search used as a motion command. For
consistency and simplicity of specification, POSIX.1‐2008 does
not permit this behavior.
Execute an ex Command
Historically, vi implementations restricted the commands that
could be entered on the colon command line (for example, append
and change), and some other commands were known to cause them to
fail catastrophically. For consistency, POSIX.1‐2008 does not
permit these restrictions. When executing an ex command by
entering :, it is not possible to enter a <newline> as part of
the command because it is considered the end of the command. A
different approach is to enter ex command mode by using the vi Q
command (and later resuming visual mode with the ex vi command).
In ex command mode, the single-line limitation does not exist.
So, for example, the following is valid:
Q
s/break here/break\
here/
vi
POSIX.1‐2008 requires that, if the ex command overwrites any part
of the screen that would be erased by a refresh, vi pauses for a
character from the user. Historically, this character could be
any character; for example, a character input by the user before
the message appeared, or even a mapped character. This is
probably a bug, but implementations that have tried to be more
rigorous by requiring that the user enter a specific character,
or that the user enter a character after the message was
displayed, have been forced by user indignation back into
historical behavior. POSIX.1‐2008 requires conformance to
historical practice.
Shift Left (Right)
Refer to the Rationale for the ! and / commands. Historically,
the < and > commands sometimes moved the cursor to the first
non-<blank> (for example if the command was repeated or with _ as
the motion command), and sometimes left it unchanged.
POSIX.1‐2008 does not permit this inconsistency, requiring
instead that the cursor always move to the first non-<blank>.
Historically, the < and > commands did not support buffer
arguments, although some implementations allow the specification
of an optional buffer. This behavior is neither required nor
disallowed by POSIX.1‐2008.
Execute
Historically, buffers could execute other buffers, and loops,
infinite and otherwise, were possible. POSIX.1‐2008 requires
conformance to historical practice. The *buffer syntax of ex is
not required in vi, because it is not historical practice and has
been used in some vi implementations to support additional
scripting languages.
Reverse Case
Historically, the ~ command ignored any associated count, and
acted only on the characters in the current line. For consistency
with other vi commands, POSIX.1‐2008 requires that an associated
count act on the next count characters, and that the command move
to subsequent lines if warranted by count, to make it possible to
modify large pieces of text in a reasonably efficient manner.
There exist vi implementations that optionally require an
associated motion command for the ~ command. Implementations
supporting this functionality are encouraged to base it on the
tildedop edit option and handle the text regions and cursor
positioning identically to the yank command.
Append
Historically, counts specified to the A, a, I, and i commands
repeated the input of the first line count times, and did not
repeat the subsequent lines of the input text. POSIX.1‐2008
requires that the entire text input be repeated count times.
Move Backward to Preceding Word
Historically, vi became confused if word commands were used as
motion commands in empty files. POSIX.1‐2008 requires that this
be an error. Historical implementations of vi had a large number
of bugs in the word movement commands, and they varied greatly in
behavior in the presence of empty lines, ``words'' made up of a
single character, and lines containing only <blank> characters.
For consistency and simplicity of specification, POSIX.1‐2008
does not permit this behavior.
Change to End-of-Line
Some historical implementations of the C command did not behave
as described by POSIX.1‐2008 when the $ key was remapped because
they were implemented by pushing the $ key onto the input queue
and reprocessing it. POSIX.1‐2008 does not permit this behavior.
Historically, the C, S, and s commands did not copy replaced text
into the numeric buffers. For consistency and simplicity of
specification, POSIX.1‐2008 requires that they behave like their
respective c commands in all respects.
Delete
Historically, lines in open mode that were deleted were scrolled
up, and an @ glyph written over the beginning of the line. In the
case of terminals that are incapable of the necessary cursor
motions, the editor erased the deleted line from the screen.
POSIX.1‐2008 requires conformance to historical practice; that
is, if the terminal cannot display the '@' character, the line
cannot remain on the screen.
Delete to End-of-Line
Some historical implementations of the D command did not behave
as described by POSIX.1‐2008 when the $ key was remapped because
they were implemented by pushing the $ key onto the input queue
and reprocessing it. POSIX.1‐2008 does not permit this behavior.
Join
An historical oddity of vi is that the commands J, 1J, and 2J are
all equivalent. POSIX.1‐2008 requires conformance to historical
practice. The vi J command is specified in terms of the ex join
command with an ex command count value. The address correction
for a count that is past the end of the edit buffer is necessary
for historical compatibility for both ex and vi.
Mark Position
Historical practice is that only lowercase letters, plus
backquote and single-quote, could be used to mark a cursor
position. POSIX.1‐2008 requires conformance to historical
practice, but encourages implementations to support other
characters as marks as well.
Repeat Regular Expression Find (Forward and Reverse)
Historically, the N and n commands could not be used as motion
components for the c command. With the exception of the cN
command, which worked if the search crossed a line boundary, the
text region would be discarded, and the user would not be in text
input mode. For consistency and simplicity of specification,
POSIX.1‐2008 does not permit this behavior.
Insert Empty Line (Below and Above)
Historically, counts to the O and o commands were used as the
number of physical lines to open, if the terminal was dumb and
the slowopen option was not set. This was intended to minimize
traffic over slow connections and repainting for dumb terminals.
POSIX.1‐2008 does not permit this behavior, requiring that a
count to the open command behave as for other text input
commands. This change to historical practice was made for
consistency, and because a superset of the functionality is
provided by the slowopen edit option.
Put from Buffer (Following and Before)
Historically, counts to the p and P commands were ignored if the
buffer was a line mode buffer, but were (mostly) implemented as
described in POSIX.1‐2008 if the buffer was a character mode
buffer. Because implementations exist that do not have this
limitation, and because pasting lines multiple times is generally
useful, POSIX.1‐2008 requires that count be supported for all p
and P commands.
Historical implementations of vi were widely known to have major
problems in the p and P commands, particularly when unusual
regions of text were copied into the edit buffer. The standard
developers viewed these as bugs, and they are not permitted for
consistency and simplicity of specification.
Historically, a P or p command (or an ex put command executed
from open or visual mode) executed in an empty file, left an
empty line as the first line of the file. For consistency and
simplicity of specification, POSIX.1‐2008 does not permit this
behavior.
Replace Character
Historically, the r command did not correctly handle the erase
and word erase characters as arguments, nor did it handle an
associated count greater than 1 with a <carriage-return>
argument, for which it replaced count characters with a single
<newline>. POSIX.1‐2008 does not permit these inconsistencies.
Historically, the r command permitted the <control>‐V escaping of
entered characters, such as <ESC> and the <carriage-return>;
however, it required two leading <control>‐V characters instead
of one. POSIX.1‐2008 requires that this be changed for
consistency with the other text input commands of vi.
Historically, it is an error to enter the r command if there are
less than count characters at or after the cursor in the line.
While a reasonable and unambiguous extension would be to permit
the r command on empty lines, it would require that too large a
count be adjusted to match the number of characters at or after
the cursor for consistency, which is sufficiently different from
historical practice to be avoided. POSIX.1‐2008 requires
conformance to historical practice.
Replace Characters
Historically, if there were autoindent characters in the line on
which the R command was run, and autoindent was set, the first
<newline> would be properly indented and no characters would be
replaced by the <newline>. Each additional <newline> would
replace n characters, where n was the number of characters that
were needed to indent the rest of the line to the proper
indentation level. This behavior is a bug and is not permitted by
POSIX.1‐2008.
Undo
Historical practice for cursor positioning after undoing commands
was mixed. In most cases, when undoing commands that affected a
single line, the cursor was moved to the start of added or
changed text, or immediately after deleted text. However, if the
user had moved from the line being changed, the column was either
set to the first non-<blank>, returned to the origin of the
command, or remained unchanged. When undoing commands that
affected multiple lines or entire lines, the cursor was moved to
the first character in the first line restored. As an example of
how inconsistent this was, a search, followed by an o text input
command, followed by an undo would return the cursor to the
location where the o command was entered, but a cw command
followed by an o command followed by an undo would return the
cursor to the first non-<blank> of the line. POSIX.1‐2008
requires the most useful of these behaviors, and discards the
least useful, in the interest of consistency and simplicity of
specification.
Yank
Historically, the yank command did not move to the end of the
motion if the motion was in the forward direction. It moved to
the end of the motion if the motion was in the backward
direction, except for the _ command, or for the G and ' commands
when the end of the motion was on the current line. This was
further complicated by the fact that for a number of motion
commands, the yank command moved the cursor but did not update
the screen; for example, a subsequent command would move the
cursor from the end of the motion, even though the cursor on the
screen had not reflected the cursor movement for the yank
command. POSIX.1‐2008 requires that all yank commands associated
with backward motions move the cursor to the end of the motion
for consistency, and specifically, to make ' commands as motions
consistent with search patterns as motions.
Yank Current Line
Some historical implementations of the Y command did not behave
as described by POSIX.1‐2008 when the '_' key was remapped
because they were implemented by pushing the '_' key onto the
input queue and reprocessing it. POSIX.1‐2008 does not permit
this behavior.
Redraw Window
Historically, the z command always redrew the screen. This is
permitted but not required by POSIX.1‐2008, because of the
frequent use of the z command in macros such as map n nz. for
screen positioning, instead of its use to change the screen size.
The standard developers believed that expanding or scrolling the
screen offered a better interface for users. The ability to
redraw the screen is preserved if the optional new window size is
specified, and in the <control>‐L and <control>‐R commands.
The semantics of z^ are confusing at best. Historical practice is
that the screen before the screen that ended with the specified
line is displayed. POSIX.1‐2008 requires conformance to
historical practice.
Historically, the z command would not display a partial line at
the top or bottom of the screen. If the partial line would
normally have been displayed at the bottom of the screen, the
command worked, but the partial line was replaced with '@'
characters. If the partial line would normally have been
displayed at the top of the screen, the command would fail. For
consistency and simplicity of specification, POSIX.1‐2008 does
not permit this behavior.
Historically, the z command with a line specification of 1
ignored the command. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Historically, the z command did not set the cursor column to the
first non-<blank> for the character if the first screen was to be
displayed, and was already displayed. For consistency and
simplicity of specification, POSIX.1‐2008 does not permit this
behavior.
Input Mode Commands in vi
Historical implementations of vi did not permit the user to erase
more than a single line of input, or to use normal erase
characters such as line erase, worderase, and erase to erase
autoindent characters. As there exist implementations of vi that
do not have these limitations, both behaviors are permitted, but
only historical practice is required. In the case of these
extensions, vi is required to pause at the autoindent and
previous line boundaries.
Historical implementations of vi updated only the portion of the
screen where the current cursor character was displayed. For
example, consider the vi input keystrokes:
iabcd<escape>0C<tab>
Historically, the <tab> would overwrite the characters "abcd"
when it was displayed. Other implementations replace only the 'a'
character with the <tab>, and then push the rest of the
characters ahead of the cursor. Both implementations have
problems. The historical implementation is probably visually
nicer for the above example; however, for the keystrokes:
iabcd<ESC>0R<tab><ESC>
the historical implementation results in the string "bcd"
disappearing and then magically reappearing when the <ESC>
character is entered. POSIX.1‐2008 requires the former behavior
when overwriting erase-columns—that is, overwriting characters
that are no longer logically part of the edit buffer—and the
latter behavior otherwise.
Historical implementations of vi discarded the <control>‐D and
<control>‐T characters when they were entered at places where
their command functionality was not appropriate. POSIX.1‐2008
requires that the <control>‐T functionality always be available,
and that <control>‐D be treated as any other key when not
operating on autoindent characters.
NUL
Some historical implementations of vi limited the number of
characters entered using the NUL input character to 256 bytes.
POSIX.1‐2008 permits this limitation; however, implementations
are encouraged to remove this limit.
<control>‐D
See also Rationale for the input mode command <newline>. The
hidden assumptions in the <control>‐D command (and in the vi
autoindent specification in general) is that <space> characters
take up a single column on the screen and that <tab> characters
are comprised of an integral number of <space> characters.
<newline>
Implementations are permitted to rewrite autoindent characters in
the line when <newline>, <carriage-return>, <control>‐D, and
<control>‐T are entered, or when the shift commands are used,
because historical implementations have both done so and found it
necessary to do so. For example, a <control>‐D when the cursor is
preceded by a single <tab>, with tabstop set to 8, and shiftwidth
set to 3, will result in the <tab> being replaced by several
<space> characters.
<control>‐T
See also the Rationale for the input mode command <newline>.
Historically, <control>‐T only worked if no non-<blank>
characters had yet been input in the current input line. In
addition, the characters inserted by <control>‐T were treated as
autoindent characters, and could not be erased using normal user
erase characters. Because implementations exist that do not have
these limitations, and as moving to a column boundary is
generally useful, POSIX.1‐2008 requires that both limitations be
removed.
<control>‐V
Historically, vi used ^V, regardless of the value of the literal-
next character of the terminal. POSIX.1‐2008 requires
conformance to historical practice.
The uses described for <control>‐V can also be accomplished with
<control>‐Q, which is useful on terminals that use <control>‐V
for the down-arrow function. However, most historical
implementations use <control>‐Q for the termios START character,
so the editor will generally not receive the <control>‐Q unless
stty ixon mode is set to off. (In addition, some historical
implementations of vi explicitly set ixon mode to on, so it was
difficult for the user to set it to off.) Any of the command
characters described in POSIX.1‐2008 can be made ineffective by
their selection as termios control characters, using the stty
utility or other methods described in the System Interfaces
volume of POSIX.1‐2017.
<ESC>
Historically, SIGINT alerted the terminal when used to end input
mode. This behavior is permitted, but not required, by
POSIX.1‐2008.
None.
ed(1p), ex(1p), stty(1p)
The Base Definitions volume of POSIX.1‐2017, Section 12.2,
Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 VI(1P)
Pages that refer to this page: ctags(1p), ed(1p), ex(1p), mailx(1p), more(1p), sh(1p)
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