centos man page for tee

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 correspond-
       ing 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 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
", <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 Technol-
       ogy -- 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)