Cron has always been one of those “scary sysadmin things” in my head. But today, I finally used it!
I have access to a private API that happens to clear it’s users if they are inactive for too long. To solve this, I decided to add a small cron job to make an API call once per month. Basically a keepalive.
Adding a cron job to my laptop was very easy. First, I made a bash script for my api call (not needed, but I felt like doing it).
#! /bin/bash curl --include --header "Accept: application/xml" '<API Endpoint Here>' --user $1:$2
Then, by running
crontab -e in my terminal, I just added a new line at the bottom of the file, discribing the task, and when it should be run.
# Edit this file to introduce tasks to be run by cron. # # Each task to run has to be defined through a single line # indicating with different fields when the task will be run # and what command to run for the task # # To define the time you can provide concrete values for # minute (m), hour (h), day of month (dom), month (mon), # and day of week (dow) or use '*' in these fields (for 'any').# # Notice that tasks will be started based on the cron's system # daemon's notion of time and timezones. # # Output of the crontab jobs (including errors) is sent through # email to the user the crontab file belongs to (unless redirected). # # For example, you can run a backup of all your user accounts # at 5 a.m every week with: # 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/ # # For more information see the manual pages of crontab(5) and cron(8) # # m h dom mon dow command 00 11 1 * * /usr/local/bin/api-keepalive.sh <username> <password>
This will run once per month, on the 1st, at 11:00.
That’s it! Stupidly simple, and I am no longer scared of cron