Add Cronjob via bash

add-cronjob.sh

#!/bin/bash

# Idea stolen from https://stackoverflow.com/questions/610839/how-can-i-programmatically-create-a-new-cron-job#13355743

addCronjob() {
    user=$(whoami)

    (crontab -u "$user" -l 2>/dev/null || echo '' ; echo "$1") \
        | sort - \
        | uniq - \
        | crontab -u "$user" -
}

# Usage
addCronjob "* * * * * echo 'boop'"