Here’s a handy way to send emails from the command line:

echo 'message' | mail -s 'subject' 'email_address'

If you know the recipient’s carrier, you can also use it to send text messages from the command line. For example, if the recipient’s number is 111-111-1111 and she’s on Verizon, you can send her a text message using the following command:

echo 'Sent from my terminal!' | 
    mail -s 'Linux is fun' '1111111111@vtext.com'

Once again, the trick here is knowing the domain name of the carrier’s Email-to-SMS Gateway. In the case of Verizon, it’s @vtext.com. Wikipedia has a handy list of other gateways here. Another trick is to send yourself an email from the phone, and the phone’s SMS gateway will be revealed in the ‘from’ field.

You can use this to create all sorts of fun shell scripts. For example, here’s one I wrote recently that tells me whether or not the VPS provider BuyVM has any VPSs in stock:

#!/bin/bash -

echo 'Is BuyVM in stock?'
while :; do
        wget -O - -q http://doesbuyvmhavestock.com/ | grep -i yes
        if [ $? == 0 ]; then
                echo 'Well, what are you waiting for?' | 
                    mail -s "BuyVM is in stock" "you@example.com"
                echo 'Yes!'
                exit 0
        else
            echo 'No'
            sleep 15m
        fi
done

It’s pretty simple. Every 15 minutes it scrapes the webpage doesbuyvmhavestock.com and sends me an email if it contains the word ‘yes’. Obviously, the success of your own script depends on how well it can parse the webpage. As you can see, my parsing routine (the grep on line 5) is pretty primitive.