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What is the difference when I put crontab entry in crontab -e (the default location is : /var/spool/cron/username ) and in /etc/crontab? I mean crond daemon will essentially execute both cron jobs. Then why there are two different ways to schedule cronjob ? Which one preferred over the other ?

Ameyj
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  • The jobs scheduled to run under /etc/crontab will run as root, the others will not? – Zlatko Mar 05 '14 at 16:17
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    what if it is /var/spool/cron/root ? then which one is preferred? – Ameyj Mar 05 '14 at 16:20
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    There's probably not a "right" answer to this - but I tend to think if it's something specific to the `root` user's account (e.g. generating some reports that get e-mailed to `root`, which forwards it to wherever) it should go in `/var/spool/cron/crontabs/root`, but if it's just a system-wide admin task, like cleaning up `/tmp` or something, then it belongs in `/etc/crontab`/`/etc/cron.d/*` (or `/etc/cron.{hourly,daily,weekly,monthly}` as appropriate). That's just my opinion, though... – twalberg Mar 05 '14 at 17:08

2 Answers2

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The difference is that the crontab command is the interface provided by the system for users to manipulate their crontabs. The /etc/crontab file is a special case file used to implement a system-wide crontab. /var/spool/cron/crontabs/$USER (or whatever the path happens to be) is an implementation detail.

If you can schedule jobs using the crontab command, you should do so.

Manually editing the contents of /etc/crontab (a) requires root access, and (b) is more error-prone. You can mess up your system that way.

If the jobs are to be run under your own user account, there's no need to use root access.

Even if the jobs are to run as root, it probably still makes more sense to use the crontab command invoked from the root account. (For one thing, it should detect syntax errors in the file.)

Personally, I don't use crontab -e. Instead, I have a crontab file that I keep in a source control system, and I use the crontab filename form of the command to install it. That way, if I mess something up, it's easy to revert to an earlier version.

Keith Thompson
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  • But if using `crontab filename` to install, and you're sure the code is fine, it doesn't really matter which of those 2 crontabs you are overwriting, as far as I know. – Jesse Nickles Nov 16 '19 at 11:34
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    @jessuppi It certainly does matter. `crontab filename` will always update your personal crontab (even if you run it as `root`), never `/etc/crontab`. The two crontabs use different syntaxes. `/etc/crontab` has an extra column specifying the user to run the command. – Keith Thompson Nov 16 '19 at 23:07
  • @KeithThompson Those are 2 great points... maybe you can update your answer to remind users of that? In our SlickStack project (FOSS), we use the `root` user crontab as there seems to be a long-held belief that `/etc/crontab` is holy and untouchable, and might one day be used by Linux distros for something system-related. Although the `root` user crontab path is a bit convoluted... – Jesse Nickles Nov 23 '19 at 18:50
  • @jessuppi: Why do you care about the path of the `root` user crontab? You should only manipulate it via the `crontab` command. – Keith Thompson Nov 23 '19 at 22:33
  • @KeithThompson I understand and do mate, but messy paths are never fun. – Jesse Nickles Nov 24 '19 at 11:23
  • @JesseNickles Messy paths are neither fun nor not fun if you ignore them, and you should. I use crontab all the time, and I honestly don't know where the crontab file is stored (though I could find out easily enough). – Keith Thompson Dec 10 '21 at 19:02
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Differences :

$PATH

(On my Red Hat 7 system)

  • Running via /etc/crontab : $PATH is /sbin:/bin:/usr/sbin:/usr/bin
  • Running via crontab -e : $PATH is /usr/bin:/bin

Access

  • Only root can access /etc/crontab
  • User can access their own /var/spool/cron/user-name

Format

  • /etc/crontab needs an extra parameter, preceding the command, which specifies the user.
  • crontab -e (/var/spool/cron/user-name) obviously does not need the user name in the crontab entry.
David Castell
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