Unix - Manual vs Automatic Log Rotation

1. Manual Log Rotation

What It Is

Manual rotation means a system administrator rotates log files by hand whenever needed.

How It Is Done

• Renaming log files

• Creating new log files

• Compressing or deleting old logs manually

Example

mv /var/log/syslog /var/log/syslog.1
touch /var/log/syslog
gzip /var/log/syslog.1

Advantages

✔ Full control over rotation
✔ Useful for emergency situations
✔ Simple for very small systems

Disadvantages

❌ Time-consuming
❌ Error-prone
❌ Easy to forget
❌ Not scalable
❌ Risk of disk full issues

2. Automatic Log Rotation

What It Is

Automatic rotation uses tools like logrotate or systemd-journal to rotate logs automatically based on rules.

How It Is Done

• Runs via cron or systemd timer

• Rotates logs based on:

  • Time (daily, weekly)

  • Size (100MB, etc.)

• Compresses and deletes logs automatically

Example (logrotate)

/var/log/syslog {
    daily
    rotate 7
    compress
}

Advantages

✔ Fully automated
✔ Prevents disk space issues
✔ Consistent and reliable
✔ Suitable for servers
✔ Supports compression and retention

Disadvantages

❌ Requires initial configuration
❌ Misconfiguration may cause loss of logs

3. Key Differences (Tabular Comparison)

4. Security & Reliability Comparison

5. When to Use Each

Use Manual Rotation When:

• Debugging or testing

• One-time emergency cleanup

• Very small or temporary systems

Use Automatic Rotation When:

• Production servers

• Multi-user systems

• Security-sensitive environments

• Compliance requirements