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bug#21416: "--" syntax for ignoring flags doesn't seem to work right wit
From: |
Eric Blake |
Subject: |
bug#21416: "--" syntax for ignoring flags doesn't seem to work right with GNU /bin/echo |
Date: |
Fri, 4 Sep 2015 16:42:48 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 09/04/2015 04:34 PM, Eric Blake wrote:
> [As it is, bash has a bug:
> $ (shopt -s xpg_echo; echo -e)
>
> should output '-e', but currently outputs nothing. Also, bash does not
> quite treat POSIXLY_CORRECT=1 (also spelled 'set -o posix') as the
> override to turn on full POSIX compliance, as it leaves xpg_echo as a
> separate knob; ideally, turning on posix compliance in bash should turn
> on xpg_echo - but enough people are used to the old behavior that it was
> decided to keep the knobs separate]
Maybe I spoke too soon. It looks like bash needs BOTH xpg_echo and posix
mode at the same time, either one in isolation is not enough:
$ for opt in '' 'shopt -s xpg_echo' 'set -o posix' \
'shopt -s xpg_echo; set -o posix'; do
bash -c "echo 'trying $opt'; ${opt:-:}; echo -e"
done
trying
trying shopt -s xpg_echo
trying set -o posix
trying shopt -s xpg_echo; set -o posix
-e
$
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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bug#21416: "--" syntax for ignoring flags doesn't seem to work right with GNU /bin/echo, Bob Proulx, 2015/09/04