ttys = ( );

open(WHO, "who|")                   or die "can't open who: $!";
while (<WHO>) {
    ($user, $tty) = split;
    push( @{$ttys{$user}}, $tty );
}

foreach $user (sort keys %ttys) {
    print "$user: @{$ttys{$user}}\n";
}
The heart 


##</code><code>##

#!/usr/bin/perl -w

use strict;

open FH, 'sipfile.m' or die "can't open file $!";

my ($call1, $sipm);
my %data1 = ( );

while (<FH>) {
      if (($call1,$sipm) = /(SIP[0-9]).+ (\d\d\d).+$/) {
      push ( @{data1{$call1}}, $sipm );
      }
}

foreach $call1 (sort keys %data1) {
   print "$data1{$call1}\n"; 
}
close FH;

##</code><code>##

Scalar value @{data1{$call1} better written as ${data1{$call1} at ./perl.m line 12.<br>
Type of arg 1 to push must be array (not hash slice) at ./perl.m line 12, near "$sipm )"
Execution of ./perl.m aborted due to compilation errors.