How do I remove the special character at the end?

Question

I have the following code in my program, which aims to return the version and subversion of Debian installed. The output from shell is read by the variables and parsed and a string formed.

#!/usr/bin/perl
use warnings;
use strict;
use Scalar::Util qw(looks_like_number);
chomp(my $distver=`cat /etc/issue`);
$distver =~ s/\\n//g;
$distver =~ s/\\/./g;
$distver =~ s/ //g;
our $enpos=-1;
for ( my $i=0; $i <length($distver); $i++ ) {
    if (looks_like_number(substr($distver, $i, 1))) {
        if ( $enpos == -1 ) { $enpos = $i; }
    }
}
print "Distro:".substr($distver, 0, $enpos)."".substr($distver, $enpos);
my $subver=substr($distver, $enpos);
$subver =~ s/\\n//g;
$subver =~ s/\\r//g;
$subver =~ s/\\f//g;
print "Subversion:".$subver."\n";

The output of the above is:

root@der:~# ./distr.pl
Distro:DebianGNU/Linux7.l
Subversion:7.l

In the output, there is an additional newline at the end, after 7.1. I had tried the regexes above in attempt to remove newline, return and form feed characters at the end, but failed.

The output of cat /etc/issue is this.

I initially tried chomp to remove newline from the output, and found that instead of removing an ending newline, it did this:

print "Distro:".substr($distver, 0, $enpos)."".substr($distver, $enpos);
my $subver=chomp(substr($distver, $enpos));
print "Subversion:".$subver."\n";

Output:

root@der:~# ./distr.pl
Distro:DebianGNU/Linux7.l
Subversion:1
root@der:~#

So why is this happening? Why does chomp (and chop) cut off more than a newline? And why is this extra newline being output?

Answer 1

chomp changes the string in place, it does not return the changed string, but the number of characters removed.

To remove newlines, use s/\n//g, the double backslash matches backslash.

Answer 2

Try it like this:

$distver =~ s/\n.*//s;