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test-and-set in bash

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# 1  
Old 06-17-2008
test-and-set in bash
I'm not talking about the assembly instruction TAS, a better name could be check-and-set Smilie Anyway, is there a way to simplify the following

Code:
if [ -z $VAR ]; then VAR="something"; fi

I have ~20 variables that should be test-and-set like this, and it really looks lame.
# 2  
Old 06-17-2008
a shorthand could be

Code:
[ -z $VAR ] && VAR="something"

# 3  
Old 06-17-2008
Code:
: ${VAR:=something} ${ANOTHER:=whatever}

The semantics of the := variable substitution operator are not exactly equivalent to what you're asking about, but perhaps it's close enough.

Note that the default values are often set on a line which begins with the colon (basically "nop") shell command. It's different from the comment in that the rest of the line is evaluated by the shell. Anyway, see your shell's manual page for details.
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