http://www.perlmonks.org?node_id=971746

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

Hi Chaps

Need some help with this, I’m attempting to try and read in the below which is system output for one of the NIC on my server.

2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:4e:97:a1 brd ff:ff:ff:ff:ff:ff

I want to be able to strip away all characters before eth1 including all white space and eveything after eth1: so I’m just left with eth1.

I have tried various regular expression but can’t seem to trap : unless you can think of a better way to do it.

Then print out back to the file handle just the NIC adapter name

This is what I have so far, not much to go on but should give oyu an idea of what im trying to do

#!/usr/bin/perl -w
my $nicount = `ip link >/tmp/nic.txt`;
open(NICFH, "/tmp/nic.txt") || die "can't open file: $!";
my @NIC = <NICFH>;
foreach my $file (@NIC) {
$file =~ s/\d\:\s//;
print $file;
}

[download]

Replies are listed 'Best First'.
Re: Remove text after and before
by johngg (Canon) on May 22, 2012 at 10:13 UTC

    Perhaps like this?

    knoppix@Microknoppix:~$ perl -E '
> $input = <<EOI;
> 2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
+ state UP qlen 1000 link/ether 00:0c:29:4e:97:a1 brd ff:ff:ff:ff:ff:f
+f
> EOI
> 
> $eth = ( split m{\s*:\s*}, $input )[ 1 ];
> say qq{->$eth<-};'
->eth1<-
knoppix@Microknoppix:~$

    [download]

    Cheers,

    JohnGG

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[d/l]

      Thanks Guys

      You have been a great help looks like I have it sorted now

      Thanks again
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Re: Remove text after and before
by Neighbour (Friar) on May 22, 2012 at 09:47 UTC
    You could replace your source data with this:
    my @NIC = split("\n", `ip link | sed -n 1~2p | cut -d':' -f2 | tr -d ' '`);
    and go from there, though that's not really the Perl way :P

    A more perlish way would be like this: 
    my @raw_data = `ip link`;
my @NIC = grep { /^\d+:\ /; } @raw_data;

for (@NIC) {
    chomp;
    s/^[0-9]+:\ ([a-z]+[0-9]*):\ .*$/$1/;
}
Data::Dump::dd(@NIC);

    [download]
    (For some reason map { s/^[0-9]+:\ ([a-z]+[0-9]*):\ .*$/$1/; } grep ... doesn't seem to work).
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      (For some reason map { s/^[0-9]+:\ ([a-z]+[0-9]*):\ .*$/$1/; } grep ... doesn't seem to work).

      That's because s/// returns the number of substitutions, not the substituted string, and map picks up the return value of the block. So adding a $_; to the end of the block might help, then the block returns the substituted text.

      Perl 6 - the future is here, just unevenly distributed
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