Cron Entry From Script

add_cron() {
    local entry="$1"
    # Read current crontab (empty if none), add the line if missing
    if ! crontab -l 2>/dev/null | grep -qF -- "$entry"; then
        (crontab -l 2>/dev/null; echo "$entry") | crontab -
        echo "Added: $entry"
    else
        echo "Already present: $entry"
    fi
}

add_cron "0 3 * * * /usr/local/bin/backup.sh >> /var/log/backup.log 2>&1"
add_cron "*/5 * * * * /usr/local/bin/health-check.sh"

# Remove a cron entry by pattern
crontab -l | grep -v 'backup.sh' | crontab -

# Show current crontab
crontab -l