COLON(P) POSIX Programmer's Manual COLON(P)
colon - null utility
: [argument ...]
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.
Special Built-In Utilities
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 COLON(P)