Editing other users' crontabs with STDIN

Rohaq · 02-23-2010, 09:30 AM

I want to edit another user's crontab with the output from STDIN. crotnab usage is apparently as follows:

Code:

crontab [file | -e | -l | -r ] [user]

But entering the following pops up with a 'proper usage' error:

Code:

cat test.cron | sudo crontab - username

Similarly, trying to take the input from a file has the same error:

Code:

sudo crontab /tmp/test.cron username

On the other hand, I can edit my own crontab with no problems:

Code:

cat test.cron | crontab

Error for all is as follows:

Code:

crontab: proper usage is: 
        crontab [file | -e | -l | -r ] [user]

I've trying to figure out the best way to do this - I want to do it from STDIN, rather than a file, since the command I'll be using outputs to STDOUT by default, however I don't even have the option to take input from a file, apparently!

If anyone could help with this, I would appreciate it.

jlliagre · 02-23-2010, 11:32 AM

The usage message is misleading. The newer one is better:

Code:

crontab: usage:
	crontab [file]
	crontab -e [username]
	crontab -l [username]
	crontab -r [username]

Rohaq · 02-23-2010, 11:35 AM

Ah, so basically you can't feed STDIN into a specific user's crontab? That's rather annoying!

Blinker_Fluid · 02-23-2010, 12:24 PM

Quote:

Originally Posted by Rohaq

Ah, so basically you can't feed STDIN into a specific user's crontab? That's rather annoying!

It's probably not the proper way to do it but you could just edit the files directly in /var/spool/cron/crontabs/ and then restart cron...

jlliagre · 02-24-2010, 12:29 AM

Quote:

Originally Posted by Rohaq

Ah, so basically you can't feed STDIN into a specific user's crontab? That's rather annoying!

Crontab doesn't handle stdin when specified as "-" but there are other ways to do it. The simpler would be:

Code:

su username "crontab /dev/stdin"