-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 10/15/15 1:34 PM, Mike Frysinger wrote:
> with bash-4.0, new compat options were introduced:
> shopt -s compat32
> and with bash-4.3, a variable was added:
> export BASH_COMPAT=3.2
>
> but things get a little weird when you want to set the compat level to
> the current version:
Unsetting all the compatNN variables and BASH_COMPAT does this. In fact,
even if you set, say, compat43, then set and unset BASH_COMPAT, the
compatibility level is set to the current version (which means that there
is no compatibility level -- it's an indication of *backwards*
compatibility, after all).
If you really want to do it, though, you can:
BASH_COMPAT=${BASH_VERSINFO[0]}.${BASH_VERSINFO[1]}
> $ echo $BASH_VERSION
> 4.3.42(1)-release
> $ shopt -s compat43
> bash: shopt: compat43: invalid shell option name
> $ export BASH_COMPAT=4.3
> <no error as DEFAULT_COMPAT_LEVEL is 43>
>
> we're interested in this in Gentoo because we want to set the current
> shell compat level to a min version even if that version is the active
> one. ideally it'd be:
> if ! shopt -s compat43 ; then
> echo "error: >=bash-4.3 required, but ${BASH_VERSION} found" >&2
> exit 1
> fi
What practical use does this have? What does Gentoo intend to do with this
requirement?
> instead we have to probe the active version ourselves:
> if ! shopt -s compat43 ; then
> if [[ ${BASH_VERSINFO[0]} -ne "4" || ${BASH_VERSINFO[1]} -ne
> "3" ]] ; t
hen
> echo ...
> exit 1
> fi
> fi
>
> the BASH_COMPAT variable isn't as useful:
I disagree. In fact, in a future version I'm going to stop introducing new
compatNN options in favor of looking at the value of BASH_COMPAT. I really
don't want to end up with 12 compatNN options.
> - possible to accidentally export and impact other shell scripts
It's kind of flip to say, but don't do that.
> - doesn't fail for <bash-4.3 versions
What?
> - when set to a bad value, $? is set to 0
Hmmm...then you don't think it's useful to print an error message in
this case? Strictly speaking, the assignment should not fail -- the
value was assigned successfully, and the warning indicates that the
assignment may not have the intended effect. Let me take a look at that
and see what I can do, though.
> - need to capture & test stderr
> which means you end up with:
> if ([[ -n $( (BASH_COMPAT=4.3) 2>&1 ) ]] ||
> [[ ${BASH_VERSINFO[0]} -lt 4 ]] ||
> [[ ${BASH_VERSINFO[0]} -eq 4 && ${BASH_VERSINFO[1]} -lt 3 ]]) ; then
> echo ...
> exit 1
> fi
> BASH_COMPAT=4.3
>
> so my request is simple: can we have compatXY added for the current versi
on ?
> so in the upcoming bash-4.4 release, get a compat44 option added.
This runs counter to the intent of the options.
Chet
- --
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
iEYEARECAAYFAlYf8EcACgkQu1hp8GTqdKsjNACdHU5aLPF3l08+wYJ/EWWKa/FH
xbEAoIkurQCIIKhw0psmBvWsjB+To5lZ
=jxes
-----END PGP SIGNATURE-----
