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
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