Install, Edit, or Remove Cron Jobs

1. Install Crontab in Batch Mode

By specifying the file name as an argument to crontab command, you can install the new cron jobs from a text file as shown below.

First create a text file with all your cron job entries.

$ cat cron-file.txt
* * * * * /bin/date >> /tmp/date-out
* * * * * /bin/ls >> /tmp/ls-out

Next, install the cron jobs from a text file as shown below.

$ crontab cron-file.txt

Note: This will overwrite the existing cron entries.

2. Edit crontab in Batch Mode

You can edit the crontab in batch mode using various methods (for example, using sed).

Example: Change output redirection from write to append for all cron jobs.

$ crontab -l
* * * * * /bin/date > /tmp/date-out
* * * * * /bin/ls > /tmp/ls-out

$ crontab -l | sed 's/>/>>/' | crontab -

$ crontab -l
* * * * * /bin/date >> /tmp/date-out
* * * * * /bin/ls >> /tmp/ls-out

3. Remove All cron jobs of the Current User

Crontab’s -r option removes all cron job for the current user. If you have appropriate privilege, you can even remove other user’s cron jobs using the -r option along with the -u user option.

Example: Remove the current user cron entries.

$ crontab -r

Example: Remove the specified user cron entries.

$ crontab -r -u USERNAME
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