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Cron Jobs for Backup

Cron is a simple scheduler and is widely available. The main risk is that cron runs with a minimal environment, so scripts that work in your interactive shell may fail silently unless you log output and control concurrency.

Quick Summary
  • Cron runs with a limited PATH and environment.
  • Always redirect stdout/stderr to a log.
  • Use flock to prevent overlapping backup runs.
  • Prefer running a script from /usr/local/bin instead of inlining a long command.

A safe cron pattern​

Create a script, make it executable, and call it from cron.

install-backup-wrapper-script.sh
sudo install -m 700 /dev/stdin /usr/local/bin/wp-backup-run <<'EOF'
#!/usr/bin/env bash
set -euo pipefail

umask 077
export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

exec /usr/local/bin/wp-backup-full
EOF

Prevent overlapping runs with flock​

Wrap the job with flock:

cron-with-flock.sh
flock -n /var/lock/wp-backup.lock /usr/local/bin/wp-backup-run

Redirect logs​

Example: daily at 02:15.

crontab-entry-example.txt
15 2 * * * flock -n /var/lock/wp-backup.lock /usr/local/bin/wp-backup-run >>/var/log/wp-backup.log 2>&1

Install a crontab entry​

Edit root crontab:

edit-root-crontab.sh
sudo crontab -e

List active cron entries:

list-root-crontab.sh
sudo crontab -l

Test from cron-like environment​

Run the script with a minimal environment:

simulate-cron-environment.sh
env -i HOME="$HOME" PATH="/usr/bin:/bin" /usr/local/bin/wp-backup-run

Alternative: systemd timers​

If your server uses systemd, timers often give better logging and dependency control.

See the timer example pattern in:

  • opt/docker-data/apps/docusaurus/site/docs/server/linux-server/09-performance-process-management/monitoring-health.mdx

Next steps​

  • Logging and verification: opt/docker-data/apps/docusaurus/site/docs/server/linux-server/10-backup-disaster-recovery/backup-logging-and-verification.mdx.
  • Alerting: opt/docker-data/apps/docusaurus/site/docs/server/linux-server/10-backup-disaster-recovery/alert-on-failed-backup-jobs.mdx.