http://www.perlmonks.org?node_id=976599

davis has asked for the wisdom of the Perl Monks concerning the following question:

*blows dust off perlmonks.org account. I've been away a while, but thought my Perl-fu was up to this rather simple task.

I believe I'm suffering from a rather simple misunderstanding of the /x modifier, and of the {} quantifiers. It's also the first time I've used the named capture buffers, but I'm not sure that matters.

Here's a complete script which should produce a match, so what have I done wrong?

#!/usr/bin/perl use warnings; use strict; use Data::Dumper; my $vg_details = ' --- Physical volumes --- PV Name /dev/dsk/c14t3d1 PV Name /dev/dsk/c15t3d1 Alternate Link PV Status available Total PE 15997 Free PE 0 Autoswitch On Proactive Polling On '; while($vg_details =~ m/^\s*PV\s+Name\s*(?<pv_name>\S+)\s*$ (^\s*PV\s+Name\s+(?<alt_link>\S+)\s+Alternate\s+Link\s*$){0,20} +# skip them ^\s*PV\s+Status\s+(?<pv_status>\S+)\s*$ ^\s*Total\s+PE\s+(?<total_pe>\S+)\s*$ ^\s*Free\s+PE\s+(?<free_pe>\d+)\s*$ ^\s*Autoswitch\s+(?<autoswitch>\S+)\s*$ ^\s*Proactive\s+Polling\s+(?<proactive_polling>\S+)\s*$/gsmx) { my $pv_name = $+{pv_name}; print "matched $pv_name"; }

The example data is slightly contrived, in that the "Alternate Link" lines are optional (and there may be many). Removing the additional 6 lines below the "PV Name" line in the regex makes it work, so have I completely confused the multi-line comment switch?

Also, I know this is a slightly ludicrous method to process VG data, but I've been handed a big, big list of "vgdisplay -v" output, and this particular edge case is failing. I've reduced it to this minimal example and my eyes still can't spot what's wrong. What silly mistake am I making?


davis