COLON(1P) POSIX Programmer's Manual COLON(1P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEcolon — null utility
This utility shall only expand command arguments. It is used when a
command is needed, as in the then condition of an if command, but noth‐
ing is to be done by the command.
See the DESCRIPTION.
The standard error shall be used only for diagnostic messages.
CONSEQUENCES OF ERRORS
The following sections are informative.
else echo $X
As with any of the special built-ins, the null utility can also have
variable assignments and redirections associated with it, such as:
x=y : > z
which sets variable x to the value y (so that it persists after the
null utility completes) and creates or truncates file z.
Section 2.14, Special Built-In Utilities
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .
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IEEE/The Open Group 2013 COLON(1P)