Re^2: How To Read Hosts File Into a Hash

[at2marty]

Thank you for your reply. I changed my code to the following.

#!/usr/bin/perl -w

use strict;

my $hostfile = "/etc/hosts";
my %hosts = ();


open FILE, "<", "$hostfile" || die "Cannot open $hostfile $!";
while (<FILE>) {
    next if /^\s*#/ ; # skip comments
    chomp;
    my ($key, $value) = split (" ", $_);
    $hosts{$key} = $value;
    }
close FILE;

The output is as follows.

Use of uninitialized value $key in hash element at hash.pl line 14, <F
+ILE> line 3.
Use of uninitialized value $key in hash element at hash.pl line 14, <F
+ILE> line 11.

Why do I get the "uninitialized error" for $key?

[toolic]

Why do I get the "uninitialized error" for $key?

My guess is your input file has a blank line:

while (<FILE>) {
    next if /^\s*#/ ; # skip comments
    next unless /\S/; # skip blank lines
    chomp;
    my ($key, $value) = split;
    $hosts{$key} = $value;
    }

See perlre

[keszler]

Your /etc/hosts file lines 3 and 11 have zero or more white space characters and nothing else. You should skip those:

while (<FILE>) {
  next if /\A\s*\z/ ; # skip blank lines
  next if /^\s*#/ ; # skip comments

Or combine the regexes:

  next if /\A\s*(?:#|\z)/ ; skip comments and blank lines