rtcwake : Wake up your system after given time.

Waking up the pc is the common need of every moderate users. In that case rtcwake is a useful utility for you. Using this utility you can wake up your linux box at any given time. So, why do we need to wake up the poor soul. Because of the following reasons:

• System clean-up when you are busy sleeping after exploiting the pc for a whole day.
• Routine System backup when you are busy attending other emergencies. 
• Running a cron job like buzzing a song to wake you up. 

The usage can be endless. To install this program. Execute commands below.

sudo apt-get install rtcwake
sudo chmod u+s /usr/sbin/rtcwake

An example of the rtcwake command can be

rtcwake -m mem -s 300

Online Crontab Tool

Crontab is a handy tool for scheduling particular tasks/commands. You can set a time for updating the system, shutting it down etc. So, to use the crontab, issue the command
>crontab -e 
This will display the crontab file which you can edit to set your tasks.
These are the options related to crontab
crontab -e    Edit your crontab file, or create one if it doesn’t already exist.
crontab -l      Display your crontab file.
crontab -r      Remove your crontab file.
crontab -v      Display the last time you edited your crontab file. (This option is only available on a few systems.)