Reading File and Inserting into Variables using Perl - perl

Question

I'm new to Perl, so please bare with my on my ignorance. What I'm trying to do is read a file (already using File::Slurp module) and create variables from the data in the file. Currently I have this setup:
use File::Slurp;
my #targets = read_file("targetfile.txt");
print #targets;
Within that target file, I have the following bits of data:
id: 123456789
name: anytownusa
1.2.3.4/32
5.6.7.8/32
The first line is an ID, the second line is a name, and all successive lines will be IP addresses (maximum length of a few hundred).
So my goal is to read that file and create variables that look something like this:
$var1="123456789";
$var2="anytownusa";
$var3="1.2.3.4/32,5.6.7.8/32,etc,etc,etc,etc,etc";
** Taking note that all the IP addresses end up grouped together into a single variable and seperated by a (,) comma.

Answer 1

File::Slurp will read the complete file data in one go. This might cause an issue if the file size is very big. Let me show you a simple approach to this problem.
Read file line by line using while loop
Check line number using $. and assign line data to respective variable
Store ips in an array and at the end print them using join
Note: If you have to alter the line data then use search and replace in the respective conditional block before assigning the line data to the variable.
Code:
#!/usr/bin/perl
use strict;
use warnings;
my ($id, $name, #ips);
while(<DATA>){
chomp;
if ($. == 1){
$id = $_;
}
elsif ($. == 2){
$name = $_;
}
else{
push #ips, $_;
}
}
print "$id\n";
print "$name\n";
print join ",", #ips;
__DATA__
id: 123456789
name: anytownusa
1.2.3.4/32
5.6.7.8/32
Demo

Answer 2

As it has been noted, there is no reason to "slurp" the whole file into a variable. If nothing else, it only makes the processing harder.
Also, why not store named labels in a hash, in this example
my %identity = (id => 123456789, name => 'anytownusa');
The code below picks up the key names from the file, they aren't hard-coded.
Then
use warnings;
use strict;
use feature 'say';
my (#ips, %identity);
my $file = 'targetfile.txt';
open my $fh, '<', $file or die "Can't open $file: $!";
while (<$fh>)
{
next if not /\S/;
chomp;
my ($m1, $m2) = split /:/; #/(stop bad syntax highlight)
if ($m1 and $m2) { $identity{$m1} = $m2; }
else { push #ips, $m1; }
}
say "$_: $identity{$_}" for keys %identity;
say join '/', #ips;
If the line doesn't have : the split will return it whole, which will be the ip and which is stored in an array for processing later. Otherwise it returns the named pair, for 'id' and 'name'.
We first skipped blank lines with next if not /\S/;, so the line must have some non-space elements and else suffices, as there is always something in $m1. We also need to remove the newline, with chomp.

Answer 3

Read the file into variables directly:
use Modern::Perl;
my ($id, $name, #ips) = (<DATA>,<DATA>,<DATA>);
chomp ($id, $name, #ips);
say $id;
say $name;
$" = ',';
say "#ips";
__DATA__
id: 123456789
name: anytownusa
1.2.3.4/32
5.6.7.8/32
Output:
id: 123456789
name: anytownusa
1.2.3.4/32,5.6.7.8/32