Thanks, Lars, for the explanation.
Dejan, can you fix it?
On Thu, Sep 23, 2010 at 4:48 PM, Lars Ellenberg
<lars.ellenb...@linbit.com> wrote:
> On Wed, Sep 22, 2010 at 08:26:43AM -0600, Serge Dubrouski wrote:
>> Thanks, Dejan -
>>
>> There was one more little patch for pgsql to replace:
>>
>> ocf_run $quietrun su $OCF_RESKEY_pgdba -c "$*"
>>
>> with
>>
>> ocf_run $quietrun su $OCF_RESKEY_pgdba -c "cd $OCF_RESKEY_pgdata; $@"
>
> Don't do that.
> shell quoting is like gamling at times.
>
> o() {
> output=`"$@" 2>&1`;
> set +x;
> echo "----- result:";
> echo "$output";
> };
> p0() { ( set -x; o su lars -c "cd . ; $@" ); }
> p1() { ( set -x; o su lars -c "cd . ; $*" ); }
>
> # invokation:
>
> The "$@" Variant:
> # p0 'printf "%s\n"' "a white space a" b c d
> + o su lars -c 'cd . ; printf "%s\n"' 'a white space a' b c d
> ++ su lars -c 'cd . ; printf "%s\n"' 'a white space a' b c d
> + output=
> + set +x
> ----- result:
>
>
> D'oh. Nothing. Why?
> Because the extra arguments have become extra arguments to su as well,
> and are no longer part of the script passed to -c.
>
> The "$*" Variant:
> # p1 'printf "%s\n"' "a white space a" b c d
> + o su lars -c 'cd . ; printf "%s\n" a white space a b c d'
> ++ su lars -c 'cd . ; printf "%s\n" a white space a b c d'
> + output='a
> white
> space
> a
> b
> c
> d'
> + set +x
> ----- result:
> a
> white
> space
> a
> b
> c
> d
>
> Not too good, but at least acceptable.
>
> All in one parameter, special case, no difference with $* and $@
> # p1 'printf "%s\n" "a white space a" b c d'
> + o su lars -c 'cd . ; printf "%s\n" "a white space a" b c d'
> ++ su lars -c 'cd . ; printf "%s\n" "a white space a" b c d'
> + output='a white space a
> b
> c
> d'
> + set +x
> ----- result:
> a white space a
> b
> c
> d
>
>
> It does not make a difference for the current use of runasowner,
> as long as you use it always with exactly one parameter.
>
> But as that is non-obvious to most, and people are going to copy'n'paste
> from that resource agent later, don't do the "$@".
>
> Expansion of $@ and $* within double quotes is very much different,
> and $@ in this context is very likely wrong, as it may pass flags
> to su which had been meant to be passed to the command run within -c.
>
> But yes, do the "cd $OCF_RESKEY_pgdata; $*".
> No problem with that.
>
> --
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
>
> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
> _______________________________________________________
> Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org
> http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev
> Home Page: http://linux-ha.org/
>
--
Serge Dubrouski.
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