Reading lines within a file (Perl)

jack.barnes · 03-16-2011, 04:37 AM

Hi All,

I am trying to read certain lines within a file and give the output of the certain lines that dont equal my value, I think showing you would be easier.

There is multiples of these inside one file.......

Code:

LV Name                     /dev/vg00/lvol1
LV Status                   available/syncd
LV Size (Mbytes)            300
Current LE                  75
Allocated PE                75
Used PV                     1

LV Name                     /dev/vg00/lvol2
LV Status                   available/syncd
etc...

I want to read everything in the file, if the status is not available then it should display the name (directly above status). If they are all availbale then do nothing.

I think I know how to do it which includes putting the info in string form and placing in hash but it is proving to be out of my skill range.

Any help is accepted!

scoban · 03-16-2011, 06:15 AM

grep -B 1 "not available" file_name

grail · 03-16-2011, 06:24 AM

@scoban - I have two issues with your solution:

1. It will return both lines, ie not just the one prior.
2. What if 'not available' is not linked against status?

@OP - Does it have to be Perl? If so, what have you tried so far?

kurumi · 03-16-2011, 06:24 AM

Ruby(1.9+)

Code:

$ ruby -ane 's=$_.gsub(/LV Name\s+/,"") if /LV Name/; print s if /LV Status/ && !/available/ ' file

jack.barnes · 03-16-2011, 06:49 AM

Grail - I am afraid the nature of the work has to be written in perl and it is actually a nagios plugin I am creating (believe it or not the nagios part of it is the easiest)

After banging my head against the wall for days, I have come up with nothing, not helpful I am aware. The following things I have down but all jumbled up just so I know what im doing!

Code:

cat mirror_status_data #diplays data
open my $output_fh, "******"
    
while (<$output_fh>){
        my $line=$_;
	$line=~s/\s+//g;

You wouldnt believe how confused I am!!!

scoban · 03-16-2011, 06:58 AM

I am assuming "not available" will shown in status line only.

Code:

grep -B 1 "not available" file_name | head -1

removes second line.

Can be called from perl using system() I think..

fogpipe · 03-16-2011, 07:39 AM

Maybe this will be of help

http://perldoc.perl.org/functions/readline.html

grail · 03-16-2011, 08:05 AM

Well I am a bit of a Perl noob, but something like this might lead you in the right direction:

Code:

#!/usr/bin/perl -w

open my $input, 'your_file_name_here';

my $keep = '';

while (<$input>)
{
    if ( $_ =~ /Status.*not available/)
    {
        print $keep;
    }
    else
    {
        $keep = $_;
    }
};

jack.barnes · 03-16-2011, 08:52 AM

Everything has been pretty helpfull so far, but im not there yet, unfortunately.

The status varies between different things, so I am after anything that is not "available" or "available/synced". Wherever this occures in the file I want to display the line above it else print "ok"

jack.barnes · 03-16-2011, 09:24 AM

This is what I have so far.

Code:

#!/usr/bin/perl -w

#check_mirror_statuss
#This plugin will allow the user to check the mirror status' and give a CRITICAL message if the status is not available.
#Author: Jack Barnes
#Version: v1.0
#This program is free software. You may copy or redistribute it under the same terms as Perl itself.

use Getopt::Long;
use warnings;
use strict;

my $file_name = "MIRROR_STATUS";

sub main {

#Counting number of current processes
    open my $output_fh, 'mirror_status_data';

#Searching file
    while (<$output_fh>){
    
#Deciding if Warning or Critical message is needed 
	if ("***LV status != available"){
	    print "****lv name";
	    print "$file_name CRITICAL - mirror status = ***LV name"; 
	    exit;
	}
	else{
	    print "$file_name OK";
	    exit;
	}
    } 
}

main ();

I have placed **** where the code needs to go, but its got me a little confuffled!

grail · 03-16-2011, 10:30 AM

So I find it a little hard to follow your logic based on the variable names, ie you have a variable called file_name but it isn't used when you open the file but is used for the message??

But using your current data, the following seems to work for me:

Code:

#!/usr/bin/perl -w

open my $input, f2;

my $keep = '';

while (<$input>)
{
    if ( $_ =~ /Status/ && $_ !~ /available(\/synced)?$/ )
    {
        print $keep;
    }
    else
    {
        $keep = $_;
    }
};

close $input

I am guessing the 'if' is the most important part for you as the rest is fairly standard stuff.

jack.barnes · 03-16-2011, 10:49 AM

Thanks grail, I have played around with that to my specifications and it pretty much what I was after!

In regards to

Quote:

you have a variable called file_name but it isn't used when you open the file but is used for the message??

this was to save typing out the name of the file continusly which is what I had to do in my last nagios plugin (Im a copy paste type of guy).

Now I have that out of the way i will try and finish this plugin off without posting for help.

Thanks Again

grail · 03-16-2011, 11:09 AM

Hey, don't be shy to ask for help ... sheesh not sure where I would be if I didn't

Glad was able to help you onto the right track