On Fri, 2010-12-03 at 00:34 +0800, Chow Loong Jin wrote:
> It appears to me that your patch only adds a : to ${var+:$var} to make it
> ${var:+:$var}, but both forms are equivalent, and tested on Ubuntu and
> Debian's
> versions of Bash. Therefore this bug does not exist in Debian, and the patch
> is
> unnecessary. I don't know if Redhat's bug truly exists, or whether it was
> patched without proper verification, though.
Actually, they're *not* the same; whether the difference is relevant is
a different question, but there is a difference.
>From bash(1):
When not performing substring expansion, using the forms documented
below, bash tests for a parameter that is unset or null. Omitting the
colon results in a test only for a parameter that is unset.
and as an example:
a...@hathi:~$ FOO=
a...@hathi:~$ echo bar${FOO+:$FOO}:baz
bar::baz
a...@hathi:~$ echo bar${FOO:+:$FOO}:baz
bar:baz
Regards,
Adam
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