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Re: null command and parameter expansion for "Display error if null or u
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From: |
Paul Jarc |
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Subject: |
Re: null command and parameter expansion for "Display error if null or unset" |
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Date: |
Mon, 31 Jul 2006 14:15:10 -0400 |
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User-agent: |
Gnus/5.110003 (No Gnus v0.3) Emacs/21.4 (gnu/linux) |
"Dave Rutherford" <dave@evilpettingzoo.com> wrote:
> On 7/31/06, Poor Yorick <org.gnu.lists.bug-bash@pooryorick.com> wrote:
>> : ${FAKEVAR?} || echo hello
>
> Try this and then run your script:
>
> export FAKEVAR="echo This could have been rm -rf $HOME"
That won't do anything. The contents of $FAKEVAR, if any, are just
passed as arguments to :, which does nothing. Since the expansion
isn't quoted, word splitting and pathname expansion are applied -
that's extra useless work, but not harmful.
paul