how to add stuff to crontab without using crontab -e

[Steven W. Orr]

On Sunday, Apr 12th 2009 at 23:23 -0000, quoth Antonio Olivares:

=>
=>Dear fellow Fedora users,
=>
=>I want to know if it is possible to edit/append to crontab without using crontab -e.  I have about 10 machines running Fedora and at the end of the day I have to manually power them off (shutdown).  For a while, I started thinking about it, well I can make a crontab to shutdown the machines at a certain time:
=>
=>Edit crontab to shutdown machines from student account at 4:15 every day(Monday-Friday) at school :)  This way I don't have to shut them down myself :)
=>
=>$ which poweroff
=>
=>
=>If crontab is empty I want to add the following to it, so that the machines can shutdown by themselves at 4:15 pm.  
=>
=># min hour day-of-month month day-of-week command
=>15 16 * * 1-5 /usr/bin/poweroff  >& /dev/null
=>
=>I can manually type this for each of the 12 machines, but I thought it would be more efficient to do something like
=>
=>#!/bin/bash
=>#
=>crontab -e << "# min hour day-of-month month day-of-week command" \
=>"15 16 * * 1-5 /usr/bin/poweroff  >& /dev/null " \
=>EOF >>
=>
=>or something similar to apply it to all machines via a usb stick and avoid the typing. How can I correct the above script to do the job, if there is way to do it.
=>
=>I have done it manually and it will work, but how can I do it with a script to do it more efficiently?  
=>
=>Thank you in advance for your help/guidance/suggestions/advice.
=>
=>Regards,
=>
=>Antonio 
=>

There have been a number of answers to your problem, none of which I like.

Your crontab is handwritten source code and needs to be treated as such. 
You may not appreciate what I'm telling you until you actually one day 
lose your crontab. Edit a file in your home directory called ~/.crontab 
and use whatever editor you like. Make your crontab ref whatever programs 
you want and then when your done, just run

crontab < ~/.crontab

to install it. You can check to see that it worked by just running 
crontab -l

Does this help?

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