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)

PROLOG         top

       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.

NAME         top

       tee — duplicate standard input

SYNOPSIS         top

       tee [−ai] [file...]

DESCRIPTION         top

       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.

OPTIONS         top

       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.

OPERANDS         top

       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.

STDIN         top

       The standard input can be of any type.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.

ASYNCHRONOUS EVENTS         top

       Default, except that if the −i option was specified, SIGINT shall be
       ignored.

STDOUT         top

       The standard output shall be a copy of the standard input.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       If any file operands are specified, the standard input shall be
       copied to each named file.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    The standard input was successfully copied to all output files.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       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.

APPLICATION USAGE         top

       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.

EXAMPLES         top

       Save an unsorted intermediate form of the data in a pipeline:

           ... | tee unsorted | sort > sorted

RATIONALE         top

       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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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)