On 03/03/10 14:05, Brian Debelius wrote:
> Hi,
>
> Looking at Bacula scripts and other scripts, I see a test for an
> empty string performed by adding an 'x' before the variable, and then
> comparing this to another string that is just an 'x'.
>
> The shell test function has a -z string test that returns true if the
> string is empty.
>
> It appears to me that more people use the 'x' comparison. Is there a
> technical reason why one would be preferable to the other?
>
> Why would you do this:
>
> if [ "x$var" = "x" ]; then
> ...
> fi
>
> Instead of this:
>
> if [ -z $var ]; then
more properly: if [ -z "$var" ]; then
> ...
> fi
I've never understood that one myself. I've always put it down to
people who don't know about the -z operator or learned shell scripting
in an environment in which it was not available.
--
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