Vineet Kumar wrote:
> * Stefan Fritsch ([EMAIL PROTECTED]) [071116 13:03]:
>> is unset. (Actually, some scripts use "${LD_LIBRARY_PATH+:
>> $LD_LIBRARY_PATH}", which seems to work, too. But this is not
>> documented in the bash man page, at least I can't find it.)
>
> The difference between ${PARAMETER:+WORD} and ${PARAMETER+WORD} is
> subtle, and you're right, it's not documented in the bash man page.
>From the bash manpage:
In each of the cases below, word is subject to tilde expansion, parame‐
ter expansion, command substitution, and arithmetic expansion. When
not performing substring expansion, bash tests for a parameter that is
unset or null; omitting the colon results in a test only for a parame‐
ter that is unset.
But I agree that I would not have found it if I did not know what to
search.
> It is part of the POSIX shell standard, though.
Yes, and posh has it. I prefer the formulation from the posh manpage:
In the above modifiers, the : can be omitted, in which case the
conditions only depend on name being set (as opposed to set and not
null). [...]
Vincent
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