I wanted Crontab shut down the system daily but it didn't do so, did I misspelled something? This is my Crontab file:

 /etc/crontab: system-wide crontab

 Unlike any other crontab you don't have to run the `crontab'

 command to install the new version when you edit this file

 and files in /etc/cron.d. These files also have username fields,

 that none of the other crontabs do.



SHELL=/bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin



 m h dom mon dow user   command

17 *    * * *   root    cd / && run-parts --report /etc/cron.hourly

25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )

52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

Shutdown every day at 02:30 am

30 0 2 * * * /sbin/shutdown -h now

It's ok but I'm a bit new to Ubuntu, so I do open Crontab -e in the Terminal an it's looks like this:

# Edit this file to introduce tasks to be run by cron.



# Each task to run has to be defined through a single line indicating with

# different fields when the task will be run and what command to run for the

# task. To define the time you can provide concrete values for minute (m), 

# hour (h), day of month (dom), month (mon), and day of week (dow) or use 

# '*' in these fields (for 'any').



# Notice that tasks will be started based on the cron's system daemon's 

# notion of time and timezones. Output of the crontab jobs (including 

# errors) is sent through email to the user the crontab file belongs to 

# (unless redirected).



# For example, you can run a backup of all your user accounts at 5 a.m 

# every week with:



# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/



# For more information see the manual pages of crontab(5) and cron(8)



# m h dom mon dow command

30 02 * /sbin/shutdown -h now

So I should type my command at the end or how? and how to save it because I'm confused.