diskspace

#!/usr/bin/env perl
# print information about file systems over a certain percentage full

use warnings;

use Getopt::Long;

my $all;                         # report all file systems
my $minimum;	# report file systems with less than this many bytes free
my $threshold;	# report file systems over this percent used
my $help;
my $default = 95;	# default threshold if no options specified

GetOptions ("help|h" => \$help,
            "all|a" => \$all,
            "minimum|m:s" => \$minimum,
            "threshold|t:s" => \$threshold)
            or usage();
if ($help) { usage(); }

# symbols for multiples of 1024 bytes
my @suffixes = ("KB", "MB", "GB", "TB", "PB", "EB");

# output format for file systems at or above threshold
format STDOUT = 
@<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< @>>>> @<
$mount,                                 $free,$suffixes[$power]
.

my $full = 0;	# number of file systems at or above threshold

@output = `df -Pk`;	# retrieve disk space information
shift @output;	# strip header
foreach my $line (@output)
{
    $\ = "\n";
    $, = "\t";

    # parse this output line
    our ($fs, $blocks, $used, $avail, $percent, $mount) = split (/\s+/, $line);

    # strip percent sign
    $percent =~ s/%$//;

    # convert to three figures plus binary suffix
    $free = $avail;
    $power = 0;
    while ($free >= 1000)
    {
        $free /= 1024;
        $power++;
    }
    $free = sprintf ("%.1f", $free);
    if (length ($free) > 3)
    {
        $free =~ s/\..*//;
    }

    # -a specified
    if (defined($all))
    {
        $full++;
        write;
    }
    # both -t and -m specified
    if (defined($threshold) && defined($minimum))
    {
        if ($percent >= $threshold &&
            $avail < $minimum)
        {
            $full++;
            write;
        }
    }
    # only -t specified
    elsif (defined($threshold))
    {
        if ($percent >= $threshold)
        {
            $full++;
            write;
        }
    }
    # only -m specified
    elsif (defined($minimum))
    {
        if ($avail < $minimum)
        {
            $full++;
            write;
        }
    }
    # neither -t nor -m specified
    else
    {
        if ($percent >= $default)
        {
            $full++;
            write;
        }
    }
}
exit $full;


# print a usage message
sub usage
{
    print "
Usage:
    diskspace [options]

Options:
    -h                 Print a message describing how to run this program
    -m bytes           Show file systems that have less than bytes bytes free
    -t percent         Show file systems that are at least percent full
";
    exit 2;
}

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