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From: | Dave Rutherford |
Subject: | Re: null command and parameter expansion for "Display error if null or unset" |
Date: | Mon, 31 Jul 2006 12:59:28 -0400 |
On 7/31/06, Poor Yorick <org.gnu.lists.bug-bash@pooryorick.com> wrote:
The following line does not perform the "echo" command. : ${FAKEVAR?} || echo hello This seems inconsistent, since the return status is set to one, not to mention that the null command is documented to return a zero exit code. It would be a convenient and concise syntax for acting on unset variables.
Try this and then run your script: export FAKEVAR="echo This could have been rm -rf $HOME" to see why not to do it this way. On the other hand, if you already know FAKEVAR is not set, why are you performing a test? Dave
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