#!/usr/bin/perl 
# randline - tchrist@perl.com
use strict;
my @addr = (0);
my $i = 0;
my $file = shift;
my $temp = 0;
if (!$file) {
    $temp = 1;
    $file = "/tmp/randline.$$";
    system "cat > $file";
    die "bad cat" if $?;
} 
unless ($file and -f $file and -T $file) {
    die "usage: $0 file\n";
} 
open(F, "< $file\0") || die "can't open $file: $!";
unlink $file if $temp;
while (<F>) {
    push @addr, tell F;
} 
pop @addr;
srand(time() ^ ($$ + ($$ << 15)));
my $lineno = int (rand @addr);
my $lineaddr = $addr[$lineno];
seek (F, $lineaddr, 0)  || die "can't seek to $lineaddr in $file: $!";
$lineno++;
print scalar <F>;