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What's wrong with this line: if ${TEST:?} ; then echo empty; fi

 
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# 1  
Old 02-23-2008
What's wrong with this line: if ${TEST:?} ; then echo empty; fi
I want to print "empty" if $TEST is empty.

TEST=
if ${TEST:?} ; then echo empty; fi

But it doesn't work. What's wrong?
# 2  
Old 02-23-2008
Code:
$ cat > foo.ksh
#!/bin/ksh
TEST=
FOO=${TEST:?empty}
$ chmod +x ./foo.ksh$ ./foo.ksh
./foo.ksh: line 3: TEST: empty
$ sed 's/^TEST=/TEST=something/' foo.ksh > foo2.ksh
$ chmod +x ./foo2.ksh
$ ./foo2.ksh
$

No need for the conditional structure, a simple variable assignment will do it.

Cheers,
ZB
# 3  
Old 02-23-2008
${TEST:?} will cause your script to exit immediately. If you want to exit more
gracefully or do some cleanup, the following method of testing for an null or
empty string may be more useful.

Code:
#!/usr/bin/ksh

TEST=

if [[ ! $TEST ]]
then
   echo "empty"
fi

 
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