System Crontab or Root Crontab

Question

System crontab:

/etc/crontab

Root crontab:

sudo crontab -u root -e

Which way is preferred? As they all run tasks within administration privilege.

Answer 1

/etc/crontab is the system wide crontab.

The format of /etc/crontab is like this:

# m h dom mon dow user      command
*   *  *   *   *  someuser  echo 'foo'

while crontab -e is per user, it's worth mentioning with no -u argument the crontab command goes to the current user's crontab. You can do crontab -e -u <username> to edit a specific user's crontab.

Notice in a per user crontab there is no 'user' field.

# m h  dom mon dow  command
*   *   *   *   *   echo 'foo'

An aspect of crontabs that may be confusing is that root also has its own crontab. e.g. crontab -e -u root will not edit /etc/crontab See Configuring cron.

In Linux distros, per user crontabs are typically stored in: /var/spool/crontabs/<username>

References

https://superuser.com/questions/290093/difference-between-etc-crontab-and-crontab-e

Answer 2

/etc/cron.d (and its siblings cron.daily/weekly/monthly) is preferred for all system crontabs. You shouldn't need to touch /etc/crontab.

It's essential to separate cron entries in multiple files based on their functionality if you are planning to manage or automate things. Files under /etc/cron.d can be easily managed by packages or configuration management tools like puppet and chef. Root's crontab OTOH is practically un-maintainable by anything other than humans.

So in short, for system stuff, you can use /etc/cron.*. If there's something you would like the root user to do, then use root's crontab. /etc/crontab should be left untouched and managed by a package.