Code Snippets

tags:
CronSchedulingSystem

Install a Cron Job from a Script

Append a cron line idempotently with grep -q before crontab.

Author: chris

// Language: Bash 

#!/usr/bin/env bash
set -euo pipefail

line="*/15 * * * * /usr/local/bin/backup.sh >/dev/null 2>&1"

( crontab -l 2>/dev/null | grep -Fqx "$line" ) || \
    ( crontab -l 2>/dev/null; printf '%s\n' "$line" ) | crontab -