oam/knowledge base/cron.md

Cron

1. TL;DR
2. Further readings
   1. Sources

TL;DR

Files in /etc/cron.hourly and similar must:

• Be scripts.
  Normal crontab files will error out.
• Be executable.
  If not executable, execution will silently fail.
• Match the Debian cron script namespace (^[a-zA-Z0-9_-]+$).
  Files with an extension won't work.

systemctl --enable --now 'crond.service'
journalctl -xefu 'crond.service'

# Validate crontab files.
crontab -T '/etc/cron.d/prometheus-backup'

# List files in given directories.
# Kinda… useless?
run-parts --list '/etc/cron.daily'

# Print the names of the scripts which would be invoked.
# '--report' is *not* available everywhere.
run-parts --report --test '/etc/cron.hourly'

# Manually run crontab files in given directories.
run-parts '/etc/cron.weekly'

Further readings

• Crontab

Sources

• Function of /etc/cron.hourly
• Use anacron for a better crontab