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Re: [PLUG] Distinguishing between environment variable with null value and one that is not set
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On Wed, 14 Oct 2009, sean finney wrote:
> i hate to tell ya, but i'm pretty sure "[[" is also non-posix :)
Few things as a horrible in UNIX as trying to write portable shell scripts.
That's why I don't, I just give dubious advice. I have good advice, too:
Don't try to write portable shell scripts. ;)
Indeed, '[[' is a reserved word with undefined behavior, as I should have
remembered. The '[' command works, or its synonym 'test' (which needs a
subshell, so there you have it).
The relevant section of the POSIX spec, for those interested:
http://www.opengroup.org/onlinepubs/009695399/utilities/toc.html
Paul
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