It would be great to be able to do stuff like grep the address book to extract contact details, edit a config file to change ring tone, manage alarms with cron use apt to update all apps etc.
I use my phone (2 to 3 year old Android) as my alarm clock. If I want to sleep in for an extra 20 mins tomorrow I need to.
1. Press clock button. 2. Press Alarm button 3. Deselect my current alarm to deactivate it 4. Press Add Alarm 5. Tap repeatedly on the "scroll wheels" to select correct time
If the phone had something resembling a CLI you could just echo the newtime + Alarm into the scheduler.
Another example I get a text message from someone who is not a contact. I want to save that number I have to open the message takes about 5 or six clicks to "copy" the number into address book.
Why can't I drop to command prompt "echo Phone no. Name >> address book
If you're a developer and have the time and effort required, you could always root/jailbreak your phone and fix the issues you have for yourself.
EDIT: it is also likely that people have already solved it, or made tools that can solve it. I know people are already running cronjobs on their iPhones, there's even an scheduling automation app and so on.
And then you accidentally use ">" instead of ">>". Woops.