Written 28 Aug 2026. This is a how-to, not a product card.

Clear old logs when the disk is tight

Before you buy a bigger drive or a NAS, see how much room the computer diary is using, then trim old entries safely.

The computer keeps a diary of what programs said. That diary can grow for months. When the disk is tight and /var looked big, this is a safe trim. You are not buying a bigger drive, a NAS, or a monitoring box for this.

Skip until you looked at disk room

If you have not checked room yet, stop. That look is see if the computer still has room. If you want to see which folders are taking the room, that is see which folders are eating the disk. Clear leftover package downloads first if you have not: clear old package downloads when the disk is tight. From the couch, ask:

df -h

Point at the line that ends in /. If Use% is fine, skip this note. If phones and laptops cannot open the house folder, fix that first: when the house share disappeared, check the computer.

What this is

journalctl is the Debian and Ubuntu tool that reads the computer diary. The same tool can tell you how big that diary is, and trim old pages. You are keeping recent words. You are not deleting the house folder, Pi-hole, or Samba. You are not installing a log app.

See how big the diary is

SSH in from the couch, then run:

journalctl --disk-usage

You should see a line like Archived and active journals take up X. A few hundred megabytes is common on a computer that has been on for weeks. A few gigabytes is worth trimming. If the number is tiny, skip the rest of this note.

Trim old entries

Keep about two weeks of diary, and drop older pages:

sudo journalctl --vacuum-time=14d

Or cap the diary at a size you pick (200 megabytes is a sensible computer ceiling):

sudo journalctl --vacuum-size=200M

Pick one. You don't need both tonight. Recent errors stay. Months-old noise goes. Don't run random rm under /var/log.

Check again

Ask about the diary size once more:

journalctl --disk-usage

Then look at disk room:

df -h

The longer look is still see if the computer still has room. If you need to read a current error, that is when something broke, look at the log. Don't buy a NAS because old diary pages filled an old laptop.

What next

Package download cleanup stays clear old package downloads when the disk is tight. Folder hunters stay see which folders are eating the disk. A second copy is a backup of the house folder. Skip a new 4TB drive this weekend.

Skip

• Skip this note if disk room is fine.
• Skip this note if the diary size is already tiny.
• Skip a NAS for this look.
• Skip a new internal drive this weekend.
• Skip deleting /var, /var/log, or /srv/share by hand.
• Skip installing a log or monitoring app tonight.