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set boolean after comparison

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# 1  
Old 03-09-2009
Question set boolean after comparison
Hi there,
Sorry if the title doesn't mean much to you, I don't know how to sum up my pb in one line.
I'd like to set a value to 0 or 1 depending on the result of a comparison. Here's what I do:
Code:
supernova:~# a=
supernova:~# isempty=$([[ -z $a ]] && echo 1 || echo 0)
supernova:~# echo $isempty
1
supernova:~# a=something
supernova:~# isempty=$([[ -z $a ]] && echo 1 || echo 0)
supernova:~# echo $isempty
0

Is there any more trivial way to do that?
Thans in advance
Santiago
# 2  
Old 03-09-2009
Depends on the shell you're using. You could use something like this:

Code:
[ -z "$a" ]&&isempty=1||isempty=0

# 3  
Old 03-09-2009
Thanks Radoulov, that's better!
I was wondering if there was a way to do something like
Code:
supernova:~# isempty=$(( -z "$a" ))
supernova:~# isempty=$(( "$a"=="" ))

But this doesn't work.
# 4  
Old 03-09-2009
Another approach:

Code:
[ ! -z "$a" ];isempty=$?

# 5  
Old 03-09-2009
Interesting!
Thanks radoulov for taking some time for me.
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