--
#!/usr/bin/perl
my $str = `type unsort.txt`;

$str = join("\n", 
		map($_->[0],
		    sort( {$a->[0] cmp $b->[0] }
			  map( [$_, (split('|', $_))[-1] ], 
			       split(/\n/, $str)
			     )
			 )
		   )
	       );

print $str;
--

##</code><code>##

--
xyz4|1026|CR
xyz3|3461|CR
dert5|3251|PR
rtyaq|251|PR
dbca|583|PR
xxxt|360|CR
--

##</code><code>##

dbca|583|PR
dert5|3251|PR
rtyaq|251|PR
xxxt|360|CR
xyz3|3461|CR
xyz4|1026|CR

##</code><code>##

sort( {$a->[1] cmp $b->[1] }

##</code><code>##

--
xyz4|1026|CR
xyz3|3461|CR
dert5|3251|PR
rtyaq|251|PR
dbca|583|PR
xxxt|360|CR
--