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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 |
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.1‐2008, 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.1‐2008, 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.1‐2008.
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.1‐2008
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.1‐2008, Chapter 8, Environment
Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2008, lseek(3p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 TEE(1P)