huschi.net

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 differ (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 op-
              erands 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  Vari-
              ables  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
       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  con-
       tinue,  but  the exit status shall be non-zero.  Otherwise, the default
       actions specified 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 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 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, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  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 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 .

IEEE/The Open Group                  2003                              TEE(1P)