Re: Regular expression quantifiers and the /gsmx modifiers

[morgon]

in reply to Regular expression quantifiers and the /gsmx modifiers

I think the problem is that $ matches BEFORE a newline and ^ matches AFTER a newline (when using /sm), but you also need to consume the newline itself.

Consider:

use strict;

my $s = <<"__end__";
hubba
bubba
__end__

print "matched 1\n" if $s =~ m/^hubba$
                               ^bubba$/smx;

print "matched 2\n" if $s =~ m/^hubba$ \n
                               ^bubba$/smx;

Here only the second regex matches because in the first after the $ matches there is still a newline left and therefore the ^ does not match. You need to consume that in the regex as the second example shows.

[davis]

Damn. I completely missed that.

#!/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($vg_details =~ m/^\s*PV\s+Name\s*(?<pv_name>\S+)\s*$ \n
    (^\s*PV\s+Name\s+(?<alt_link>\S+)\s+Alternate\s+Link\s*$ \n){0,20}
+   # skip them
    ^\s*PV\s+Status\s+(?<pv_status>\S+)\s*$ \n
    ^\s*Total\s+PE\s+(?<total_pe>\S+)\s*$ \n
    ^\s*Free\s+PE\s+(?<free_pe>\d+)\s*$ \n
    ^\s*Autoswitch\s+(?<autoswitch>\S+)\s*$ \n
    ^\s*Proactive\s+Polling\s+(?<proactive_polling>\S+)\s*$ \n/gsmx) {
    my $pv_name           = $+{pv_name};
    print "matched $pv_name";
}

Seems to DWIM. I genuinely cannot believe I've been gawping at that for so long. My thanks.