Sorting variables in perl - perl

Question

Here is the code:
#!/usr/bin/perl
use warnings;
use strict;
my #user;
my $count = 0;
my #test;
my #last = qx(last);
my #logins;
# Opens the file /etc/passwd and puts the users with an uid
# over 1000 but less that 65000 into an array.
open( my $passwd, "<", "/etc/passwd") or die "/etc/passwd failed to open.\n";
while (my $lines = <$passwd>) {
my #splitarray = split(/\:/, $lines );
if( $splitarray[2] >= 1000 && $splitarray[2] < 65000) {
$user[$count] = $splitarray[0];
#print "$user[$count]\n";
$count++;
}
}
close $passwd;
for my $i (0 .. $#user) {
my $counter = 0;
#logins =qx(last $user[$i]);
for my $j (0 .. $#logins) {
if ($logins[$j] =~ /$user[$i]/) {
$counter++;
}
}
print $user[$i] . ":" . $counter . "\n";
}
And the output from this looks like this:
user1:15
user2:3
user3:6
user4:2
How can i sort this so that it shows the users with the most logins at the top? I tried with a hash but couldn't seem to get it right. Since they are not arrays i don't know how to sort them.

Answer 1

You only have one login counter. In order to sort the users by login count, you will need each user's login count.
my %logins_by_user;
for my $user (#users) {
$logins_by_user{$user} = grep /^\Q$user\E /, `last '$user'`;
}
for my $user (
sort { $logins_by_user{$b} <=> $logins_by_user{$a} || $a cmp $b } #users
) {
print("$user: $logins_by_user{$user}\n");
}

Answer 2

Here's a version which uses a hash and prints the users sorted by login count:
#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;
open(my $passwd, "<", "/etc/passwd") or die "/etc/passwd failed to open.\n";
my %login_count;
while (<$passwd>) {
my #splitarray = split(/\:/);
if ($splitarray[2] >= 1000 && $splitarray[2] < 65000) {
my $user = $splitarray[0];
my #logins = qx(last $user);
# Remove lines that don't mention the user name
#logins = grep /$user/, #logins;
# Using an array in scalar context returns the number of items in the array
$login_count{$user} = #logins;
}
}
close $passwd;
# List users sorted by login count
say "$_ : $login_count{$_}"
for sort { $login_count{$a} cmp $login_count{$b} } keys %login_count;