Well, only if you 'use warnings', the compiler tells you that $1 has never been defined, and thus, can not be printed. If you want to capture "lib" in $1, then you need to use parenthesis in your regular expression. Like so:

use v5.10;
use warnings;
use strict;

my $var;
$var = "path_to_my_lib";
$var =~ m/(lib)/;
say $1;

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Which prints the captured "lib" (and gives no warnings).

$1, $2.. etc are weird variables. You can not assign them a value, and they disappear when they go out of scope, or a new regexp is encountered. You can solve it in a few ways, for example, test it before using it: 

if($1){
        say $1;
}

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or test the regular expression to match:

if( $var =~ m/(foo)/ ){
        say $1;
}else{
        say "no match found";
}

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In reply to Re: Use of uninitialized value $1 by FreeBeerReekingMonk
in thread Use of uninitialized value $1 by Pazitiff

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