cronie (Cron Scheduler)

System 2026-08-28

cronie is the standard cron daemon — it runs commands on a schedule defined in crontab files. It is pre-installed and active by default on Shani OS.

For most recurring tasks, systemd timers are the recommended alternative: they integrate with journalctl for logging, support calendar expressions and monotonic intervals, and handle missed runs via Persistent=true. Use cron when you need the simplicity of a single-line schedule, compatibility with scripts that assume cron, or per-user jobs without root.

Crontab Syntax

# ┌── minute (0–59)
# │ ┌── hour (0–23)
# │ │ ┌── day of month (1–31)
# │ │ │ ┌── month (1–12)
# │ │ │ │ ┌── day of week (0–7, 0 and 7 = Sunday)
# │ │ │ │ │
# * * * * *  command to run

Common schedule examples:

Schedule	Meaning
`*`	Every minute
`0`	Every hour (on the hour)
`0 3 *`	Daily at 03:00
`0 3 0`	Every Sunday at 03:00
`0 3 1`	First of every month at 03:00
`/15 *`	Every 15 minutes
`0 9-17 1-5`	Every hour from 9 to 17, Mon–Fri

User Crontabs

# Edit your own crontab
crontab -e

# List your crontab
crontab -l

# Remove your crontab entirely
crontab -r

# Edit another user's crontab (root only)
sudo crontab -e -u youruser

# List another user's crontab
sudo crontab -l -u youruser

Example User Crontab

# Send output to a log file instead of local mail
MAILTO=""

# Run a backup script daily at 3 AM
0 3 * * * /home/user/scripts/backup.sh >> /home/user/logs/backup.log 2>&1

# Sync documents to cloud every 30 minutes
*/30 * * * * rclone sync ~/Documents gdrive:Documents --quiet

# Clear temp files every Sunday at midnight
0 0 * * 0 find /tmp -user $USER -mtime +7 -delete

Tip: Redirect both stdout and stderr to a log file with >> /path/to/log 2>&1. Without redirection, cron mails output to the local user — set MAILTO="" to suppress mail silently.

System Crontabs

System-wide cron jobs are placed directly in /etc/crontab or as files in these directories (no crontab editing required — just drop a script in the right directory):

Directory	Frequency
`/etc/cron.hourly/`	Every hour
`/etc/cron.daily/`	Once daily
`/etc/cron.weekly/`	Once weekly
`/etc/cron.monthly/`	Once monthly

Scripts placed in these directories must be executable and must not have a file extension:

sudo cp myscript.sh /etc/cron.daily/myscript
sudo chmod +x /etc/cron.daily/myscript

For custom schedules, add a line to /etc/crontab:

# /etc/crontab — note the extra 'username' field before the command
0 4 * * * root /usr/local/bin/maintenance.sh

Service Management

# cronie is enabled by default — check its status
systemctl status cronie

# Restart if jobs stop running after a config change
sudo systemctl restart cronie

# View cron execution logs
journalctl -u cronie -f

# See recent cron activity (last 50 lines)
journalctl -u cronie -n 50

Cron vs Systemd Timers

Prefer systemd timers when:

You need the output captured in journalctl automatically
The job must run at boot if a scheduled run was missed (Persistent=true)
The job is already a systemd service
You want precise control over the environment (working directory, user, resource limits)

Prefer cron when:

You need a quick per-user scheduled task without root
The schedule is simple and the one-liner format is sufficient
You are adapting an existing cron-based script

See the Backup & Recovery page for an example of a systemd user timer running a restic backup.

Troubleshooting

Issue	Solution
Job not running	Check `journalctl -u cronie` for errors; verify the script is executable (`chmod +x`); test the command manually as the cron user
Job runs but does nothing	Cron has a minimal `PATH` — use full paths to binaries (e.g., `/usr/bin/rsync` not `rsync`), or set `PATH=` at the top of the crontab
Output being mailed to root	Add `MAILTO=""` to suppress, or `MAILTO=youruser` to redirect; ensure Exim is running if you want mail delivery
Missed jobs after suspend/hibernate	cron does not catch up missed jobs after sleep — use a systemd timer with `Persistent=true` instead
Editing crontab opens wrong editor	Set `VISUAL` or `EDITOR` env variable: `export EDITOR=nano`