Rather than trying to parse the the df output yourself, you may find it easier to work with the
Filesys::Df module.
To send an e-mail to yourself, you should look into one of the many modules that exist to make this easy. I like MIME::Lite.
Update: Here is some (untested) code to work with. You will have to modify the email message with your e-mail addresses, and you might want to tweak the language of the Subject and Data (body text) to suit your style. Otherwise, the script reads the percent disk used from / and e-mails you if the percentage if greater than a threshold amount (in this case 90%)
#!/usr/bin/perl
use strict;
use warnings;
use Filesys::Df;
use MIME::Lite;
my $disk_info = df("/");
my $threshold = 90;
my $disk_percent;
if (defined($disk_info)){
my $disk_percent = $disk_info->{per};
}
if ($disk_percent > $threshold) {
my $message = MIME::Lite->new (
From =>'diskwatcher@yourcomputer.com',
To =>'fixitguy@othercomputer.com',
Cc =>'someonewhocares@somedomain.com',
Subject =>'ALERT: Im in ur disk usin ur inodes!',
Data => "It appears that the disk use threshold is
+ approaching the limit defined in your helpful script. You currently
+have $disk_percent percent used. Perhaps you should check on this."
);
$message -> send ;
}