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Manual Reference Pages  - COLON (P)

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colon - null utility

CONTENTS

Synopsis
Description
Options
Operands
Stdin
Input Files
Environment Variables
Asynchronous Events
Stdout
Stderr
Output Files
Extended Description
Exit Status
Consequences Of Errors
Application Usage
Examples
Rationale
Future Directions
See Also
Copyright

: [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:

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.

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 .

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