Check free disk space on each filesystem with df
Show total, used, and available space plus usage percentage for every mounted filesystem in human-readable units.
01Command
$ df -h02What it does
Each row is one mounted filesystem: the device, size, used, avail, Use%, and mount point. Ignore the 'Filesystem' rows for tmpfs, udev, and loop devices — the one whose mount point is / is your root filesystem. Watch the Avail column on the root and /home partitions; when a filesystem hits 100%, services start failing to write. On ext4/btrfs a few percent is reserved for root, so df shows less free than a non-root user can actually use, and for deleted-but-open files use lsof +L1 to find processes holding them.
03Risk
04Undo
✓No undo needed — this command does not change persistent state.
05Sources
- df(1) — report file system disk space usageEvidence: The df man page documents '-h' / '--human-readable' as printing sizes in powers of 1024 with human-readable units like G.
Last verified: 2026-09-17 · Category: Files & Folders
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