A full drive on Linux can sneak up on you — updates fail, programs act strange, and there is no big warning popup. One short command tells you exactly how much space you have left on every drive.
Run it
- Open a terminal (usually Ctrl + Alt + T).
- Type df -h and press Enter.
- That’s it — you get a table of every mounted drive and how full it is.
Read the table
- Size — how big the drive or partition is.
- Used / Avail — how much is taken, and how much is still free.
- Use% — the number to watch most.
- Mounted on — where that drive shows up, like / for your main system drive.
The -h part matters: it makes the sizes human-readable, in GB and MB instead of raw blocks that are hard to read.
What to watch for
Find the row mounted on / — that’s your main drive. If Use% is in the high 80s or 90s, it’s time to clear space: clear out old downloads, remove programs you don’t use, or move big files to another drive. Letting it hit 100% can stop updates and even keep you from logging in.
One command, five seconds, and you know exactly where your disk stands.
