What is the use of crontab command in Unix?

What is the use of crontab command in Unix?

The crontab command submits, edits, lists, or removes cron jobs. A cron job is a command run by the cron daemon at regularly scheduled intervals. To submit a cron job, specify the crontab command with the -e flag. The crontab command invokes an editing session that allows you to create a crontab file.

How do I view crontab in Unix?

You can find them in /var/spool/cron/crontabs. The tables contain the cron jobs for all users, except the root user. The root user can use the crontab for the whole system. In RedHat-based systems, this file is located at /etc/cron.

How do I assign a user to crontab?

How to Limit crontab Command Access to Specified Users

  1. Become the root role.
  2. Create the /etc/cron. d/cron. allow file.
  3. Add the root user name to the cron. allow file.
  4. Add the user names, one user name per line. Include users that will be allowed to use the crontab command.

Does crontab run as root?

The root user crontab Like any other user, root has a user crontab. Essentially the same as any other user crontab, you are editing the root crontab when you run sudo crontab -e . Jobs scheduled in the root user crontab will be executed as root with all of its privileges.

How do you create a cron job in Unix?

Manually creating a custom cron job

  1. Log into your server via SSH using the Shell user you wish to create the cron job under.
  2. You are then asked to choose an editor to view this file. #6 uses the program nano which is the easiest option.
  3. A blank crontab file opens. Add the code for your cron job.
  4. Save the file.

How do I view crontab in Linux?

  1. View Current Logged-In User’s Crontab entries : To view your crontab entries type crontab -l from your unix account.
  2. View Root Crontab entries : Login as root user (su – root) and do crontab -l.
  3. To view crontab entries of other Linux users : Login to root and use -u {username} -l.

How do I view crontab?

The crontab -l command displays the contents of a crontab file much the same way that the cat command displays the contents of other types of files. You do not have to change the directory to /var/spool/cron/crontabs directory (where crontab files are located) to use this command.

What user is crontab run as?

root
2 Answers. Show activity on this post. They all run as root . If you need otherwise, use su in the script or add a crontab entry to the user’s crontab ( man crontab ) or the system-wide crontab (whose location I couldn’t tell you on CentOS).

Does crontab run as root or user?