zhenya@zhenya-work:~$ cat 66.pl
#!/usr/bin/perl -w

my $a = '1111.2222.4444';

my $b = $a.';lol';

print "a before = ".$a."\n";

my $c = $a .= ';lol';

print "a after = ".$a."\n";
print "b = ".$b."\n";
print "c = ".$c."\n";

zhenya@zhenya-work:~$ perl 66.pl
a before = 1111.2222.4444
a after = 1111.2222.4444;lol
b = 1111.2222.4444;lol
c = 1111.2222.4444;lol