NAME

colon — null utility

SYNOPSIS

DESCRIPTION

This utility shall only expand command arguments.

EXIT STATUS

Zero.

The following section is informative.

RATIONALE

The colon (:), or null utility, 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. Example:

3.14 Special Built-in Utilities 247

: ${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.