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TEE(1P)                    POSIX Programmer's Manual                   TEE(1P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

NAME
       tee - duplicate standard input

SYNOPSIS
       tee [-ai][file...]

DESCRIPTION
       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 File Read, Write, and Creation .

OPTIONS
       The tee utility shall conform to the Base Definitions volume of  IEEE Std 1003.1-2001,  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
       The following operands shall be supported:

       file   A pathname of an output file. Processing of at least 13 file operands shall be supported.


STDIN
       The standard input can be of any type.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       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 IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for  the  prece-
              dence 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  exam-
              ple, 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 writ-
              ten to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .


ASYNCHRONOUS EVENTS
       Default, except that if the -i option was specified, SIGINT shall be ignored.

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

STDERR
       The standard error shall be used only for diagnostic messages.

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

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       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
       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 speci-
       fied in Utility Description Defaults apply.

       The following sections are informative.

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


              ... | tee unsorted | sort > sorted

RATIONALE
       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 alterna-
       tive 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
       IEEE Std 1003.1-2001.

       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  IEEE Std 1003.1-2001  requires
       functionality equivalent to using O_APPEND; see File Read, Write, and Creation .

FUTURE DIRECTIONS
       None.

SEE ALSO
       Introduction, cat, the System Interfaces volume of IEEE Std 1003.1-2001, lseek()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  Issue  6,  Copyright (C) 2001-2003 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 Stan-
       dard,  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 .



IEEE/The Open Group                  2003                              TEE(1P)