1COLON(1P)                  POSIX Programmer's Manual                 COLON(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       colon — null utility
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SYNOPSIS

15       : [argument...]
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DESCRIPTION

18       This utility shall only expand command arguments.  It is  used  when  a
19       command is needed, as in the then condition of an if command, but noth‐
20       ing is to be done by the command.
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OPTIONS

23       None.
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OPERANDS

26       See the DESCRIPTION.
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STDIN

29       Not used.
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INPUT FILES

32       None.
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ENVIRONMENT VARIABLES

35       None.
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ASYNCHRONOUS EVENTS

38       Default.
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STDOUT

41       Not used.
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STDERR

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

47       None.
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EXTENDED DESCRIPTION

50       None.
51

EXIT STATUS

53       Zero.
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CONSEQUENCES OF ERRORS

56       Default.
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58       The following sections are informative.
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APPLICATION USAGE

61       None.
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EXAMPLES

64       : ${X=abc}
65       if     false
66       then   :
67       else   echo $X
68       fi
69       abc
70
71       As with any of the special built-ins, the null utility  can  also  have
72       variable assignments and redirections associated with it, such as:
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75           x=y : > z
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77       which  sets  variable  x  to the value y (so that it persists after the
78       null utility completes) and creates or truncates file z.
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RATIONALE

81       None.
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FUTURE DIRECTIONS

84       None.
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SEE ALSO

87       Section 2.14, Special Built-In Utilities
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90       Portions of this text are reprinted and reproduced in  electronic  form
91       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
92       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
93       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
94       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
95       event of any discrepancy between this version and the original IEEE and
96       The Open Group Standard, the original IEEE and The Open Group  Standard
97       is  the  referee document. The original Standard can be obtained online
98       at http://www.opengroup.org/unix/online.html .
99
100       Any typographical or formatting errors that appear  in  this  page  are
101       most likely to have been introduced during the conversion of the source
102       files to man page format. To report such errors,  see  https://www.ker‐
103       nel.org/doc/man-pages/reporting_bugs.html .
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107IEEE/The Open Group                  2017                            COLON(1P)
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