The reason the regex doesn't work is because of this portion: (\d*)\w+\s+. What that does is search for zero or more digits and puts them in a capture group (\d*), as long as the next character is a word char (\w+), followed by at least one whitespace (\s+).

A digit is a word character. Since the only thing immediately after the proc ID is whitespace, the \w+ steals the last digit from it, before the next whitespace \s+. It only takes the last one, because \d* is greedy, and will gulp everything as far as it can until the regex doesn't match, then it backtracks.

The regex can be simplified a bit: qr|$owner\s+(\d+).*\s+$processName$|. Explained:

qr|
  $owner        # proc owner
  \s+           # one or more whitespace
  (\d+)         # capture one or more digits
  .*            # everything up until...
  \s+           # the last whitespace
  $processName  # proc name
  $             # end of string
|x

[download]

In action:

use warnings;
use strict;
use feature 'say';

getPids('top', 'ubuntu');

sub getPids{
    my ($processName,$owner) = @_;
    my $ps;
    my $pid;
    my $command = "/bin/ps auwwwx | grep $processName | grep -v grep |
+ grep -v 'sh -c' ";

    $ps = `$command`;

    # print $ps;

    my @lines = split( "\n",$ps);

    # print @lines;

    foreach my $line (@lines){
        if ($line =~ qr|$owner\s+(\d+).*\s+$processName$|){
            say "Found $processName in getPids() owned by $owner. PID 
+is $1";
        }else{
            say "Loser";
        }
    }
}

[download]

Output:

Found top in getPids() owned by ubuntu. PID is 9377

# orig:
ubuntu    9377  0.0  0.1  23668  1600 pts/2    S+   18:23   0:00 top

[download]

In reply to Re: Regex and PID issue by stevieb
in thread Regex and PID issue by JonesyJones

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