tee(1p) - c7

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

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       tee - duplicate standard input
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SYNOPSIS

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

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

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

36       The following operands shall be supported:
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38       file   A pathname of an output file. Processing of at least 13 file op‐
39              erands shall be supported.
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STDIN

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

46       None.
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ENVIRONMENT VARIABLES

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

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

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

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

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

89       None.
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EXIT STATUS

92       The following exit values shall be returned:
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94        0     The standard input was successfully copied to all output files.
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96       >0     An error occurred.
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CONSEQUENCES OF ERRORS

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

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

115       Save an unsorted intermediate form of the data in a pipeline:
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117
118              ... | tee unsorted | sort > sorted
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RATIONALE

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

142       None.
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COPYRIGHT

149       Portions of this text are reprinted and reproduced in  electronic  form
150       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
151       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
152       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
153       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
154       event of any discrepancy between this version and the original IEEE and
155       The Open Group Standard, the original IEEE and The Open Group  Standard
156       is  the  referee document. The original Standard can be obtained online
157       at http://www.opengroup.org/unix/online.html .
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161IEEE/The Open Group                  2003                              TEE(1P)