On Mon, Jan 30, 2012 at 09:24:19PM +0100, Dejan Muhamedagic wrote:
> > As for the regular expression like ^ or $, it looks like working as
> > expected with -z option in my quick tests.
> > Do you have any examples that it may break the configuration?
> 
> For instance, what I see here in the status page is also a PID at
> the beginning of line:
> 
> xen-d:~ # wget -q -O- -L --no-proxy  --bind-address ::1 
> http://[::1]/server-status | grep ^PID
> PID Key: <br />
> xen-d:~ # wget -q -O- -L --no-proxy  --bind-address ::1 
> http://[::1]/server-status | grep -z ^PID
> xen-d:~ # echo $?
> 1

different versions of grep in various distributions seem to behave
differently with -z and ^:

distro;
grep --version | head -n1;
printf "A\nB\nC\n" | grep -q -z ^B ; echo $?

etch        grep (GNU grep) 2.5.1   0
lenny       GNU grep 2.5.3          0
squeeze     GNU grep 2.6.3          1   breaks
lucid       GNU grep 2.5.4          0

rhel4       grep (GNU grep) 2.5.1   1   breaks
rhel5       grep (GNU grep) 2.5.1   0
rhel6       GNU grep 2.6.3          1   breaks

sles9       grep (GNU grep) 2.5.1   1   breaks
sles10      grep (GNU grep) 2.5.1   1   breaks
sles11      GNU grep 2.5.2          1   breaks
sles11-sp1  GNU grep 2.5.2          1   breaks


So neither distros nor grep version seem to agree
if "^" is supposed to be equivalent to pcre /^/m or /\A/ ;-)

Best practices for monitoring apache with pacemaker
would be to have some dedicated page print out
either a text/plain "ALL OK" only.
Or, in case something is wrong, anything with arbitrary diagnostic
output, if any, which reliably does not containing that string.

> But we could just as well reduce to the default regular
> expression to '</ *html *>'. If nobody objects :)

As the default regex only checks for basically "any" response that
remotely looks like it may have something to do with html output,
that should be fine.

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
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