Print variable after closing the file in Perl - perl

Question

Below code works fine but I want $ip to be printed after closing the file.
use strict;
use warnings;
use POSIX;
my $file = "/tmp/example";
open(FILE, "<$file") or die $!;
while ( <FILE> ) {
my $lines = $_;
if ( $lines =~ m/address/ ) {
my ($string, $ip) = (split ' ', $lines);
print "IP address is: $ip\n";
}
}
close(FILE);
sample data in /tmp/example file
$cat /tmp/example
country us
ip_address 192.168.1.1
server dell

Answer 1

This solution looks for the first line that contains ip_address followed by some space and a sequence of digits and dots
Wrapping the search in a block makes perl delete the lexical variable $fh. Because it is a file handle, that handle will also be automatically closed
Note that I've used autodie to avoid the need to explicitly check the status of the open call
This algorithm will find the first occurrence of ip_address and stop reading the file immediately
use strict;
use warnings 'all';
use autodie;
my $file = '/tmp/example';
my $ip;
{
open my $fh, '<', $file;
while ( <$fh> ) {
if ( /ip_address\h+([\d.]+)/ ) {
$ip = $1;
last;
}
}
}
print $ip // 'undef', "\n";
output
192.168.1.1

Answer 2

Store all ips in an array and you'll then have it for later processing.
The shown code can also be simplified a lot. This assumes a four-number ip and data like that shown in the sample
use warnings;
use strict;
use feature 'say';
my $file = '/tmp/example';
open my $fh, '<', $file or die "Can't open $file: $!";
my #ips;
while (<$fh>) {
if (my ($ip) = /ip_address\s*(\d+\.\d+\.\d+\.\d+)/) {
push #ips, $ip;
}
}
close $fh;
say for #ips;
Or, once you open the file, process all lines with a map
my #ips = map { /ip_address\s*(\d+\.\d+\.\d+\.\d+)/ } <$fh>;
The filehandle is here read in a list context, imposed by map, so all lines from the file are returned. The block in map applies to each in turn, and map returns a flattened list with results.
Some notes
Use three-argument open, it is better
Don't assign $_ to a variable. To work with a lexical use while (my $line = <$fh>)
You can use split but here regex is more direct and it allows you to assign its match so that it is scoped. If there is no match the if fails and nothing goes onto the array

Answer 3

use warnings;
use strict;
my $file = "test";
my ( $string,$ip);
open my $FH, "<",$file) or die $!;
while (my $lines = <FH>) {
if ($lines =~ m/address/){
($string, $ip) = (split ' ', $lines);
}
}
print "IP address is: $ip\n";
This will give you the output you needed. But fails in the case of multiple IP match lines in the input file overwrites the last $ip variable.