CrontabManager

PHP library to manage programmatically GNU/Linux cron jobs.

It enables you to :

• Deal with your cron jobs in PHP.
• Create new Cron jobs.
• Update existing cron jobs.
• Manage cron jobs of others users than runtime user using some sudo tricks (see below).

Requirements

• PHP 5.3+
• crontab command-line utility (should be already installed in your distribution).
• sudo, if you want to manage crontab of another user than runtime user without running into right issues (see below)

Installation

The library can be installed using Composer.

composer require tiben/crontab-manager ~1.0

Usage

The library is composed of three classes:

• CrontabJob is an entity class which represents a cron job.
• CrontabRepository is used to persist/retrieve your cron jobs.
• CrontabAdapter handles cron jobs persistance in the crontab.

Instantiate the repository

In order to work, the CrontabRepository needs an instance of CrontabAdapter.

$crontabRepository = new CrontabRepository(new CrontabAdapter());

Create new Job and persist it into the crontab

Suppose you want to create a new job which consists of launching the command "df >> /tmp/df.log" every day at 23:30. You can do it in two ways.

• In Pure oo way :

  $crontabJob = new CrontabJob();
  $crontabJob
      ->setMinutes(30)
      ->setHours(23)
      ->setDayOfMonth('*')
      ->setMonths('*')
      ->setDayOfWeek('*')
      ->setTaskCommandLine('df >> /tmp/df.log')
      ->setComments('Logging disk usage'); // Comments are persisted in the crontab
  

• From raw cron syntax string using a factory method :

  $crontabJob = CrontabJob::createFromCrontabLine('30 23 * * * df >> /tmp/df.log');
  

You can now add your new cronjob in the crontab repository and persist all changes to the crontab.

$crontabRepository->addJob($crontabJob);
$crontabRepository->persist();

Find a specific cron job from the crontab repository and update it

Suppose we want to modify the hour of an already existing cronjob. Finding existings jobs is done using some regular expressions. The regex is applied to the entire crontab line.

$results = $crontabRepository->findJobByRegex('/Logging\ disk\ usage/');
$crontabJob = $results[0];
$crontabJob->setHours(21);
$crontabRepository->persist();

Remove a cron job from the crontab

You can remove a job like this :

$results = $crontabRepository->findJobByRegex('/Logging\ disk\ usage/');
$crontabJob = $results[0];
$crontabRepository->removeJob($crontabJob);
$crontabRepository->persist();

Note: Since cron jobs are internally matched by reference, they must be previously obtained from the repository or previously added.

Work with the crontab of another user than runtime user

This feature allows you to manage the crontab of another user than the user who launched the runtime. This can be useful when the runtime user is www-data but the owner of the crontab you want to edit is your own linux user account.

To do this, simply pass the username of the crontab owner as parameter of the CrontabAdapter constructor. Suppose you are www-data and you want to edit the crontab of user bobby:

$crontabAdapter = new CrontabAdapter('bobby');
$crontabRepository = new CrontabRepository($crontabAdapter);

Using this way you will propably run into user rights issues. This can be handled by editing your sudoers file using 'visudo'.
If you want to allow user www-data to edit the crontab of user bobby, add this line:

www-data        ALL=(bobby) NOPASSWD: /usr/bin/crontab

which tells sudo not to ask for password when user www-data calls crontab as user bobby using sudo

Now, you can access to the crontab of user bobby like this :

$crontabAdapter = new CrontabAdapter('bobby', true);
$crontabRepository = new CrontabRepository($crontabAdapter);

Note the second parameter true of the CrontabAdapter constructor call. This boolean tells the CrontabAdapter to use sudo internally when calling crontab.

Enable or disable a cron job

You can enable or disable your cron jobs by using the setEnabled() method of a CronJob object accordingly :

$crontabJob->setEnabled(false);

This will prepend your cron job with a # in your crontab when persisting it.

Write your own adapter

Additionally, if you cannot read another user's crontabs or if you are on a distributed architecture where crons are not run on the machine executing the jobs, you can create any other Adapter for your architecture by implementing the CrontabAdapterInterface.

You can then instantiate the CrontabRepository with your adapter.

Unit tests

Tests have been written using PHPUnit and require version 5.3+. To execute tests:

$ phpunit <crontab-library-path>/tests

If you installed the library using Composer and installed dev-dependencies you can execute them using included PHPUnit as dependency:

$ ./vendor/bin/phpunit <crontab-library-path>/tests

Contributions

... are welcome :)