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

6       tee - duplicate standard input
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SYNOPSIS

9       tee [-ai][file...]
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DESCRIPTION

12       The  tee utility shall copy standard input to standard output, making a
13       copy in zero or more files. The tee utility shall not buffer output.
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15       If the -a option is not specified, output files shall be  written  (see
16       File Read, Write, and Creation .
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OPTIONS

19       The  tee  utility  shall  conform  to  the  Base  Definitions volume of
20       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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22       The following options shall be supported:
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24       -a     Append the output to the files.
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26       -i     Ignore the SIGINT signal.
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OPERANDS

30       The following operands shall be supported:
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32       file   A pathname of an output file. Processing of at least 13 file op‐
33              erands shall be supported.
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STDIN

37       The standard input can be of any type.
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INPUT FILES

40       None.
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ENVIRONMENT VARIABLES

43       The following environment variables shall affect the execution of tee:
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45       LANG   Provide  a  default value for the internationalization variables
46              that are unset or null. (See  the  Base  Definitions  volume  of
47              IEEE Std 1003.1-2001,  Section  8.2,  Internationalization Vari‐
48              ables for the precedence of internationalization variables  used
49              to determine the values of locale categories.)
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51       LC_ALL If  set  to a non-empty string value, override the values of all
52              the other internationalization variables.
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54       LC_CTYPE
55              Determine the locale for  the  interpretation  of  sequences  of
56              bytes  of  text  data as characters (for example, single-byte as
57              opposed to multi-byte characters in arguments).
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59       LC_MESSAGES
60              Determine the locale that should be used to  affect  the  format
61              and contents of diagnostic messages written to standard error.
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63       NLSPATH
64              Determine the location of message catalogs for the processing of
65              LC_MESSAGES .
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ASYNCHRONOUS EVENTS

69       Default, except that if the -i option was specified,  SIGINT  shall  be
70       ignored.
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STDOUT

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

76       The standard error shall be used only for diagnostic messages.
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OUTPUT FILES

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

83       None.
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EXIT STATUS

86       The following exit values shall be returned:
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88        0     The standard input was successfully copied to all output files.
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90       >0     An error occurred.
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CONSEQUENCES OF ERRORS

94       If a write to any successfully opened file  operand  fails,  writes  to
95       other  successfully opened file operands and standard output shall con‐
96       tinue, but the exit status shall be non-zero.  Otherwise,  the  default
97       actions specified in Utility Description Defaults apply.
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99       The following sections are informative.
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APPLICATION USAGE

102       The  tee  utility  is usually used in a pipeline, to make a copy of the
103       output of some utility.
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105       The file operand is technically optional, but tee  is  no  more  useful
106       than cat when none is specified.
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EXAMPLES

109       Save an unsorted intermediate form of the data in a pipeline:
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111
112              ... | tee unsorted | sort > sorted
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RATIONALE

115       The  buffering  requirement  means that tee is not allowed to use ISO C
116       standard fully buffered or line-buffered writes. It does not mean  that
117       tee has to do 1-byte reads followed by 1-byte writes.
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119       It  should  be  noted  that  early  versions  of BSD ignore any invalid
120       options and accept a single '-' as an  alternative  to  -i.  They  also
121       print a message if unable to open a file:
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123
124              "tee: cannot access %s\n", <pathname>
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126       Historical  implementations ignore write errors. This is explicitly not
127       permitted by this volume of IEEE Std 1003.1-2001.
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129       Some historical implementations  use  O_APPEND  when  providing  append
130       mode;  others use the lseek() function to seek to the end-of-file after
131       opening the file without O_APPEND. This volume of  IEEE Std 1003.1-2001
132       requires  functionality  equivalent  to  using O_APPEND; see File Read,
133       Write, and Creation .
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FUTURE DIRECTIONS

136       None.
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SEE ALSO

139       Introduction   ,   cat   ,   the   System    Interfaces    volume    of
140       IEEE Std 1003.1-2001, lseek()
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COPYRIGHT

143       Portions  of  this text are reprinted and reproduced in electronic form
144       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
145       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
146       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
147       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
148       event of any discrepancy between this version and the original IEEE and
149       The  Open Group Standard, the original IEEE and The Open Group Standard
150       is the referee document. The original Standard can be  obtained  online
151       at http://www.opengroup.org/unix/online.html .
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155IEEE/The Open Group                  2003                               TEE(P)