Another approach is read the file2 content and split each line based on ':', and save in a hash, key will be 'enable_pad','c_pad','b_pad',etc and other string as value.

Read file1 and check each line exists in hash or not, if exists print it.

use strict;
use warnings;


open my $FILE2, "<", "file2.txt" or die "Cannot open file2 file: $!";
open my $FILE1, "<", "file1.txt" or die "Cannot open file1 file: $!";

my %hash;
while (my $eachline = <$FILE2>) {
    chomp($eachline);
    my($key,$value)=split(':',$eachline,2);
    $hash{$key}=$value;
}

while (my $line = <$FILE>) {
    chomp($line)
    if(exists $hash{$line})
    {
     print $line:$hash{$line}
    }
    else{print "$line does not exist in file2"}
}
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