Originální popis anglicky:
colon - null utility
Návod, kniha: POSIX Programmer's Manual
: [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 nothing is to be done by the command.
None.
See the DESCRIPTION.
Not used.
None.
None.
Default.
Not used.
The standard error shall be used only for diagnostic messages.
None.
None.
Zero.
Default.
The following sections are informative.
None.
: ${X=abc}
if false
then :
else echo $X
fi
abc
As with any of the special built-ins, the null utility can also have variable
assignments and redirections associated with it, such as:
which sets variable
x to the value
y (so that it persists after
the null utility completes) and creates or truncates file
z.
None.
None.
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 Technology -- 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
.
