Journalctl Vacuum Script Linux

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)

journal-vacuum.sh

#!/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

Systemd journal vacuum shell script Linux

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

Systemd Journal Vacuum Shell Script (Log Disk Cleanup)

What this script does

Prerequisites

Step 1: Save the script

Step 2: Full script (scroll to read)

Step 3: Configure settings

Step 4: Test manually

Schedule with cron

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