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

meili100 · #1 (**permalink**) 02-23-2008

I want to print "empty" if $TEST is empty.

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

But it doesn't work. What's wrong?

zazzybob · #2 (**permalink**) 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

fpmurphy · #3 (**permalink**) 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

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Checking the Empty line in csv file	sollins	Shell Programming and Scripting	4	05-15-2008 08:48 AM
how to echo the file contents LINE BY LINE	newbie168	Shell Programming and Scripting	4	02-22-2006 06:43 AM
if test for empty and non-existing file	GNMIKE	Shell Programming and Scripting	3	10-21-2005 03:51 AM
empty line	YoYo	Shell Programming and Scripting	4	09-22-2005 12:14 AM
printing an empty line in a file (perl)	kfad	Shell Programming and Scripting	3	05-07-2005 04:10 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by