[CLUE-Tech] bash question

[Keith Hellman]

Hmmpha!

typeset -p VAR 2>&1 >/dev/null ; test $?

--- Keith Hellman <kehellman at yahoo.com> wrote:
> 
> Does anyone know how to determine if bash environmental variable exists?
> 
> Note, I know of ( test -z "${VAR}" ); but this doesn't tell me if the
> var
> EXISTS, it just tells me if it expands to a non-empty string.
> 
> I could do ( set |grep VAR >/dev/null ); test $?
> but this requires an invokation of grep, which seems wasteful.
> 
> readonly does not return an error value when VAR does not exist.
> 
> I could write an external program to inspect the environment, but this
> would only detect exported vars; it also has the same downside of
> grep...
> 
> It seems strange that this simply query is not available - I must be
> missing something in the docs.
> 
> I'm twiddling with the set builtin now - I think I can coerce it into a
> valid test...
> 
> The upside is that I have to scan the docs well, so I keep finding bash
> features I always wished I had :^)
> 
> TIA
> 
> 
> =====
> Keith E. Hellman
> kehellman at yahoo.com
> 
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=====
Keith E. Hellman
kehellman at yahoo.com

__________________________________________________
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