Creating a cronjob through script

Question

Is there any way to create a cronjob in an automated way (script)?

The only way i know how to create a cronjob is through contab -e which creates a temporary conf file that is, once modified and exited, merged with the actual conf file in /var/spool/cron/crontabs (this file can't be modified directly).

In particular what i'm trying to do is package a script that needs to be run every minute. When the user installs the package, the cronjob needs to be added and there in lies my problem.

So: I need a script to create a script that runs my script, not that confusing right? :P

Barmar · Accepted Answer · 2015-01-31 18:03:14Z

1

You can use

crontab filename

to install filename as the user's crontab. So your script can do something like:

crontab -l > crontab.txt # Get current crontab
echo "0 12 * * * /path/to/script" >>crontab.txt #Add a new entry
crontab crontab.txt # install new crontab

answered Jan 31, 2015 at 18:03

Barmar

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4 Comments

Jack Pettersson Over a year ago

That is absolutely brilliant. I had no idea you could specify a "template" crontab file as an argument for the program. And your solution for compatibility with already existing jobs was a bonus. Thanks alot :)

Barmar Over a year ago

When you're wondering how to do things, don't you look at man pages?

subhro Over a year ago

I am also looking for the same but instead of txt file can I use csv?

Barmar Over a year ago

@subhro The format of a crontab file is pretty specific, it's not a CSV file. You could write a script that converts a CSV file to crontab format.

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