discard lines after match

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

I need help on this one all! I have tried various ways, hash, array, seek. I need to discard all lines that match the __DISCARD__below. The rest I need to save off or print. Thank you!


use strict;
use warnings;

my (%map,@tmp,$line,$vhost,$next_line);
open (MAP, "-|", "/usr/ios/cli/ioscli lsmap -all") or die $!;
while (<MAP>) {
    next if $_ =~ /^$/;
    next if $_ =~ /--.*/;
    next if $_ =~ /^SVSA.?/;
    #push @tmp, (split(" ", $vh, 0 ));
    if ( /^vhost/i ) {
        my $pos = tell $fh;
        my $next_line = <$fh>;
        seek $fh, $pos, 0;
    }
}

__OUT__
vhost0          U9117.MMD.218A8B7-V2-C2                      0x0000000
+b
VTD                   vtscsi0
Status                Available
LUN                   0x8100000000000000
Backing device        l02duapofdev_r1.58ff94782d7c325acc49a8dd9c04bb1e
Physloc
Mirrored              N/A

vhost1          U9117.MMD.218A8B7-V2-C12                     0x0000000
+3
VTD                   NO VIRTUAL TARGET DEVICE FOUND

vhost2          U9117.MMD.218A8B7-V2-C13                     0x0000000
+4
VTD                   NO VIRTUAL TARGET DEVICE FOUND

vhost8          U9117.MMD.218A8B7-V1-C19                     0x0000000
+a

VTD                   vtscsi36
Status                Available
LUN                   0x8100000000000000
Backing device        l02dudbofqa2_a1.45b2b49e9b5d2e2a54279a67fab75306
Physloc
Mirrored              N/A

VTD                   vtscsi37
Status                Available
LUN                   0x8200000000000000
Backing device        l02dudbofqa2_r1.0d0657fb7a38e5afe50956bc8fedfb2e
Physloc
Mirrored              N/A

__DISCARD__
vhost1          U9117.MMD.218A8B7-V2-C12                     0x0000000
+3
VTD                   NO VIRTUAL TARGET DEVICE FOUND

vhost2          U9117.MMD.218A8B7-V2-C13                     0x0000000
+4
VTD                   NO VIRTUAL TARGET DEVICE FOUND
[download]

Comment on discard lines after match Download Code

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Re: discard lines after match by Laurent_R (Canon) on Nov 10, 2014 at 21:49 UTC
Hmm, not sure I really understand what your problem is, but if you just want to discard all lines after __DISCARD__ tag (including that line itself), then you just need to add this code line in your while loop: `last if /^__DISCARD__/;` [download] Now, the problem is that your program isn't doing anything useful with the data being read at this point. I would assume that you want to do something with the lines you are reading and that you don't filter out with your regexes, perhaps printing them to STDOUT or to a file, or possibly storing them in an array or something else for further processing. In addition, just one minor comment: `next if $_ =~ /--./; next if $_ =~ /^SVSA.?/;` [download] The `.` and `.?` seem to be pointless here. You could have: `next if $_ =~ /--/; next if $_ =~ /^SVSA/;` [download] which would yield the same results (except that this second version might probably be slightly more efficient, but that would be hardly noticeable, even with large input). This is really secondary, but it seems to indicate some misunderstandings in the comprehension of how regexes work. So, you are discarding lines matching `--`, presumably because `--` might indicate the beginning of a comment (it does in some programming languages), but if this is the case, you should do it only if the `--` comes at the beginning of the line, so that you might prefer something like this: `next if $_ =~ /^--/;` [download] or possibly `next if $_ =~ /^\s--/; # also removing lines having -- with some lead +ing white spaces` [download] Similarly, discarding the "empty" lines might be better written: `next if $_ =~ /^\s$/; # also removing lines with only white spaces` [download]	[reply] [d/l] [select]
Re: discard lines after match by boftx (Deacon) on Nov 10, 2014 at 20:22 UTC
Not knowing the full size of the data set this might be overkill, but... It looks like you can start a hash for each vhost you see, and stick the name of it in $vh or whatever. Then if you see "NO VIRTUAL" simply delete the hash and go on to the next line. In the hash itself you would collect the data elements for each VTD in its own hash. When you see the next vhost tag push the hash you just build onto an array of hashref. Once you see the end of the data ("__DISCARD__") break out of the loop and loop through the array, formating and printing or processing as desired. You must always remember that the primary goal is to *drain the swamp* even when you are hip-deep in alligators.	[reply]