Python: How to handle 'crontab' command?

Question

We know the crontab command is used for scheduled tasks in Linux.

I want to write a Python script. Its function is to receive some data (these data are related to crontab setting) and execute a 'crontab' command in order to reset the content of the user's crontab file.

I know how to execute external Linux commands in Python. But when you execute the crontab command (e.g. crontab -u xxx -e), you need to interact with an editor to modify the user's crontab file. (Suppose I don't know where the file is. For new users, crontab will generate a new file anyway. And I don't execute the command as the root user).

So the question is, how can I just execute crontab in Python? Is there any way to avoid interacting with an editor to modify the user's crontab file in Python?

My OS is ubuntu 14.01.

Answer 1

You could use python-crontab.

Installation

sudo -H pip install python-crontab

Concepts

• A cron is a time-based job scheduler which is related to a user.
• A job has a command and a comment and is "attached" to a cron.
• A job is executed by the cron it is attached to at given times.

Code examples

List system cron jobs:

from crontab import CronTab
cron = CronTab(tabfile='/etc/crontab', user=False)  # system users cron
# cron  = CronTab(user=True)  # current users cron
# cron  = CronTab(user='username')  # other users cron
for job in cron:
    print(job)

Create a new job:

job = cron.new(command='/foo/bar', comment='SomeID')

Enable / disable job:

job.enable()
job.enable(False)

Find an existing job by comment:

iter = cron.find_comment('ID or some text')

Remove Items::

cron.remove( job )
cron.remove_all('echo')
cron.remove_all(comment='foo')
cron.remove_all(time='*/2')

Clear entire cron of all jobs::

cron.remove_all()