Backups, log rotation, report generation — anything that runs at the same time daily belongs to a scheduler. The catch is that most scheduled jobs fail silently, so this page covers that too.

cron (Linux, macOS) 

  crontab -e        # edit
crontab -l        # list
crontab -r        # delete everything (careful)

The format is five fields:

  min hour day month weekday  command
 *    *    *    *      *
ExpressionMeaning
0 3 * * *Daily at 03:00
*/15 * * * *Every 15 minutes
0 9 * * 1-5Weekdays at 09:00
0 0 1 * *Midnight on the first of the month
@rebootAt boot

For example:

  0 3 * * * /usr/local/bin/backup.sh >> /var/log/backup.log 2>&1

Three reasons cron jobs fail

  1. PATH is different. cron runs in a minimal environment, so docker, node, and python come back as “command not found.” → Use absolute paths.
      0 3 * * * /opt/homebrew/bin/docker system prune -af
  2. Environment variables are missing. .zshrc is never read. Define what you need inside the script, or read it from a file.
  3. Output disappears. Without redirection, error messages go nowhere. → Always append >> logfile 2>&1.

launchd (preferred on macOS)

launchd is the supported mechanism on macOS, and it will run a job you missed while the machine was asleep.

~/Library/LaunchAgents/com.me.backup.plist:

  <?xml version="1.0" encoding="UTF-8"?>
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.me.backup</string>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/bash</string>
        <string>/Users/me/scripts/backup.sh</string>
    </array>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Hour</key><integer>3</integer>
        <key>Minute</key><integer>0</integer>
    </dict>
    <key>StandardOutPath</key>
    <string>/tmp/backup.log</string>
    <key>StandardErrorPath</key>
    <string>/tmp/backup.err</string>
</dict>
</plist>
  
  launchctl load ~/Library/LaunchAgents/com.me.backup.plist
launchctl list | grep com.me.backup
launchctl start com.me.backup          # run now, to test
launchctl unload ~/Library/LaunchAgents/com.me.backup.plist

systemd timers (Linux servers) 

  # /etc/systemd/system/backup.service
[Unit]
Description=Nightly backup

[Service]
Type=oneshot
ExecStart=/usr/local/bin/backup.sh
  
  # /etc/systemd/system/backup.timer
[Unit]
Description=Run backup daily

[Timer]
OnCalendar=*-*-* 03:00:00
Persistent=true

[Install]
WantedBy=timers.target
  
  sudo systemctl enable --now backup.timer
systemctl list-timers
journalctl -u backup.service -n 50

Logs collect in journalctl, and Persistent=true catches up missed runs. On a server this beats cron.

Noticing failures 

  #!/bin/bash
set -euo pipefail

trap 'curl -fsS -X POST "$SLACK_WEBHOOK" \
  -d "{\"text\":\"Backup failed on $(hostname)\"}"' ERR

/usr/local/bin/backup.sh
curl -fsS "$HEALTHCHECK_URL"     # ping only on success

The dead-man’s-switch pattern is the valuable one. Ping only on success and alert when the ping doesn’t arrive, and you also catch the case where the script never ran at all.

Next

To connect services to each other → n8n

Edit this page

Last updated 19 Aug 2026, 00:00 UTC. history