Systemd Journal Vacuum Shell Script (Log Disk Cleanup)

When /var/log/journal fills your disk, this journalctl vacuum script safely trims old logs and enforces size limits.

What this script does

• Shows journal disk usage before and after
• Vacuums logs older than N days
• Optional size cap with –vacuum-size
• Logs actions for audit trail
• Safe to schedule weekly from cron

Prerequisites

• systemd journal
• Root or sudo access

Step 1: Save the script

sudo nano /usr/local/bin/journal-vacuum.sh
sudo chmod +x /usr/local/bin/journal-vacuum.sh

Step 2: Full script (scroll to read)

#!/usr/bin/env bash
set -euo pipefail

KEEP_DAYS=7
MAX_SIZE="500M"
LOG="/var/log/journal-vacuum.log"

log(){ echo "[$(date '+%F %T')] $*" | tee -a "$LOG"; }

log "Journal usage before:"
journalctl --disk-usage | tee -a "$LOG"

log "Vacuuming logs older than ${KEEP_DAYS} days"
journalctl --vacuum-time="${KEEP_DAYS}d" >> "$LOG" 2>&1

if [[ -n "$MAX_SIZE" ]]; then
  log "Vacuuming to max size: $MAX_SIZE"
  journalctl --vacuum-size="$MAX_SIZE" >> "$LOG" 2>&1
fi

log "Journal usage after:"
journalctl --disk-usage | tee -a "$LOG"
log "Journal vacuum completed"

Scroll inside the box to read the full script.

Step 3: Configure settings

• KEEP_DAYS — keep logs for this many days (default 7)
• MAX_SIZE — optional max journal size e.g. 500M
• Also set SystemMaxUse= in /etc/systemd/journald.conf for permanent limit

Step 4: Test manually

journalctl --disk-usage

sudo /usr/local/bin/journal-vacuum.sh

Schedule with cron

sudo crontab -e

Add:

0 4 * * 0 /usr/local/bin/journal-vacuum.sh >> /var/log/journal-vacuum.log 2>&1

Related tutorials

• Linux Backup Shell Script: Files & Database to Remote Server
• Cron Jobs in Linux: Schedule Tasks with crontab
• SSH Key Authentication on Linux Servers

Terminal screenshot is an original illustration created for Gnome IT Solutions (blog.gnomeitsolutions.com).