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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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TTY(1P) POSIX Programmer's Manual TTY(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.
tty — return user's terminal name
tty
The tty utility shall write to the standard output the name of
the terminal that is open as standard input. The name that is
used shall be equivalent to the string that would be returned by
the ttyname() function defined in the System Interfaces volume of
POSIX.1‐2017.
The tty utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
None.
While no input is read from standard input, standard input shall
be examined to determine whether or not it is a terminal, and, if
so, to determine the name of the terminal.
None.
The following environment variables shall affect the execution of
tty:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error and informative messages written to
standard output.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
If standard input is a terminal device, a pathname of the
terminal as specified by the ttyname() function defined in the
System Interfaces volume of POSIX.1‐2017 shall be written in the
following format:
"%s\n", <terminal name>
Otherwise, a message shall be written indicating that standard
input is not connected to a terminal. In the POSIX locale, the
tty utility shall use the format:
"not a tty\n"
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Standard input is a terminal.
1 Standard input is not a terminal.
>1 An error occurred.
Default.
The following sections are informative.
This utility checks the status of the file open as standard input
against that of an implementation-defined set of files. It is
possible that no match can be found, or that the match found need
not be the same file as that which was opened for standard input
(although they are the same device).
None.
None.
None.
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, isatty(3p),
ttyname(3p)
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 TTY(1P)
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