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Full Discussion: difference in the two test operators
Top Forums Shell Programming and Scripting difference in the two test operators Post 302587794 by zulfi123786 on Friday 6th of January 2012 02:56:57 AM
Old 01-06-2012
difference in the two test operators
could any one please help me understand the difference between double square bracket test operator and single square bracket test operator.

I have seen one difference with the below code but not sure which one has to be used and when:

Code:
 
unix79:z54402:/data/ds/scripts $ cat > T
one,,two
unix79:z54402:/data/ds/scripts $ z=`cat T|cut -d, -f2,2`
unix79:z54402:/data/ds/scripts $ if [[ -z $z ]]
> then echo success
> else echo fail
> fi
success
unix79:z54402:/data/ds/scripts $ if [ -z $z ]
> then echo success
> else echo fail
>  fi
ksh: test: 0403-004 Specify a parameter with this command.
fail
unix79:z54402:/data/ds/scripts $

 

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