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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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TEE(1P) POSIX Programmer's Manual TEE(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.
tee — duplicate standard input
tee [-ai] [file...]
The tee utility shall copy standard input to standard output,
making a copy in zero or more files. The tee utility shall not
buffer output.
If the -a option is not specified, output files shall be written
(see Section 1.1.1.4, File Read, Write, and Creation.
The tee utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-a Append the output to the files.
-i Ignore the SIGINT signal.
The following operands shall be supported:
file A pathname of an output file. If a file operand is '-',
it shall refer to a file named -; implementations shall
not treat it as meaning standard output. Processing of
at least 13 file operands shall be supported.
The standard input can be of any type.
None.
The following environment variables shall affect the execution of
tee:
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.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default, except that if the -i option was specified, SIGINT shall
be ignored.
The standard output shall be a copy of the standard input.
The standard error shall be used only for diagnostic messages.
If any file operands are specified, the standard input shall be
copied to each named file.
None.
The following exit values shall be returned:
0 The standard input was successfully copied to all output
files.
>0 An error occurred.
If a write to any successfully opened file operand fails, writes
to other successfully opened file operands and standard output
shall continue, but the exit status shall be non-zero. Otherwise,
the default actions specified in Section 1.4, Utility Description
Defaults apply.
The following sections are informative.
The tee utility is usually used in a pipeline, to make a copy of
the output of some utility.
The file operand is technically optional, but tee is no more
useful than cat when none is specified.
Save an unsorted intermediate form of the data in a pipeline:
... | tee unsorted | sort > sorted
The buffering requirement means that tee is not allowed to use
ISO C standard fully buffered or line-buffered writes. It does
not mean that tee has to do 1-byte reads followed by 1-byte
writes.
It should be noted that early versions of BSD ignore any invalid
options and accept a single '-' as an alternative to -i. They
also print a message if unable to open a file:
"tee: cannot access %s\n", <pathname>
Historical implementations ignore write errors. This is
explicitly not permitted by this volume of POSIX.1‐2017.
Some historical implementations use O_APPEND when providing
append mode; others use the lseek() function to seek to the end-
of-file after opening the file without O_APPEND. This volume of
POSIX.1‐2017 requires functionality equivalent to using O_APPEND;
see Section 1.1.1.4, File Read, Write, and Creation.
None.
Chapter 1, Introduction, cat(1p)
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, lseek(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 TEE(1P)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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