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

13       colon — null utility
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SYNOPSIS

16       : [argument...]
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DESCRIPTION

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

24       None.
25

OPERANDS

27       See the DESCRIPTION.
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STDIN

30       Not used.
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INPUT FILES

33       None.
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ENVIRONMENT VARIABLES

36       None.
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ASYNCHRONOUS EVENTS

39       Default.
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STDOUT

42       Not used.
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STDERR

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

48       None.
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EXTENDED DESCRIPTION

51       None.
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EXIT STATUS

54       Zero.
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CONSEQUENCES OF ERRORS

57       Default.
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59       The following sections are informative.
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APPLICATION USAGE

62       None.
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EXAMPLES

65       : ${X=abc}
66       if     false
67       then   :
68       else   echo $X
69       fi
70       abc
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72       As with any of the special built-ins, the null utility  can  also  have
73       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, 2013 Edition, Standard for Information Technology
92       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
93       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
94       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
95       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
96       event of any discrepancy between this version and the original IEEE and
97       The  Open Group Standard, the original IEEE and The Open Group Standard
98       is the referee document. The original Standard can be  obtained  online
99       at http://www.unix.org/online.html .
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101       Any  typographical  or  formatting  errors that appear in this page are
102       most likely to have been introduced during the conversion of the source
103       files  to  man page format. To report such errors, see https://www.ker‐
104       nel.org/doc/man-pages/reporting_bugs.html .
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108IEEE/The Open Group                  2013                            COLON(1P)
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