[root@devel3 root]# cat diskfree.pl
#!/usr/bin/perl

use Filesys::DiskFree;

$handle = new Filesys::DiskFree;
$handle->df();
my $device = $ARGV[0] || "/";
print "The $device device is ".$handle->device($device)."\n";
print "It has ".$handle->avail($device)." bytes available\n";
print "It has ".$handle->total($device)." bytes total\n";
print "It has ".$handle->used($device)." bytes used\n";

[root@devel3 root]# ./diskfree.pl
The / device is /dev/sda3
It has 79425527808 bytes available
It has 142137049088 bytes total
It has 55491371008 bytes used

[root@devel3 root]# ./diskfree.pl /boot
The /boot device is /dev/sda1
It has 31190016 bytes available
It has 47755264 bytes total
It has 14099456 bytes used

[root@devel3 root]# ./diskfree.pl /dev/sda1
The /dev/sda1 device is /dev/sda1
It has 31190016 bytes available
It has 47755264 bytes total
It has 14099456 bytes used
[root@devel3 root]#