System command execution using Perl - regex

Question

I have a Perl script which runs a perforce command and stores the result in a variable $command.
Then it is stored in a file log.txt, and by using a regex the relevant data is taken out.
When I run that command alone the following things pop out:
4680 p4exp/v68 PJIANG-015394 25:34:19 IDLE none
8869 unnamed p4-python R integration semiconductor-project-trunktip turbolinuxclient 01:33:52 IDLE none
8870 unnamed p4-python R integration remote-trunktip-osxclient 01:33:52
The code goes as follows:
#! /usr/bin/env perl
use strict;
use warnings;
use autodie;
my $command = qx |p4 monitor show -ale|;
open FH, '>>', "log.txt";
print FH $command;
close FH;
open my $log_fh, '<', '/root/log.txt';
my %stat;
while ($line = <$log_fh>) {
chomp $line;
next if not $line =~ /(\d+)\s+/;
my $killid = $1;
if ($line =~ /R\s+integration/ and $line =~ /IDLE\s+none$/) {
my $killid_details = $line;
$stat{$killid} = $killid_details;
}
}
close $log_fh;
my $killpro;
foreach my $kill (keys %stat) {
print "$kill\n";
}
The following gets the number 8869 but how to do it without log.txt. Is using an array a better way to do it or hash is fine?
Please correct me as I am still learning.

Answer 1

Seems like your main stumbling block is getting line-by-line input for your loop?
Splitting on newlines should do the trick:
my $killid;
my #lines = split("\n", $command); #split on newlines
for my $line (#lines) {
next if not $line =~ /(\d+)\s+/;
my $id = $1;
if ($line =~ /R\s+integration/ and $line =~ /IDLE\s+none$/){
$killid = $id;
}
}
One caveat: you mentioned an output of 8870, but I'm getting 8869. The regexps you gave are looking for a line with "integration" and "IDLE none", and for your example input that appears to match 8869.
A hash is fine, though if you're using only one key in it (which seems to be the case), you might as well just use a single variable.

Answer 2

If you assign the result of a qx construct to an array instead of a scalar, then it will be split into lines automatically for you. This code demonstrates.
use strict;
use warnings;
my #lines = qx|p4 monitor show -ale|;
my %stat;
for my $line (#lines) {
chomp $line;
next unless $line =~ /(\d+)\s+/;
my $killid = $1;
if ($line =~ /R\s+integration/ and $line =~ /IDLE\s+none$/) {
$stat{$killid} = $line;
}
}
print "$_\n" for keys %stat;