df – report filesystem disk space usage
df displays disk space usage for filesystems. Essential for monitoring storage capacity.
Synopsis
df [OPTIONS] [FILE...]
Common Options
| Option | Description |
|---|---|
-h | Human-readable sizes (KB, MB, GB) |
-H | Human-readable with SI units (1000 not 1024) |
-T | Show filesystem type |
-i | Show inode usage instead of blocks |
-a | Include pseudo filesystems |
-l | Local filesystems only |
-t TYPE | Only show specific filesystem type |
Examples
Basic usage
$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 103081248 45234567 52581234 47% /
tmpfs 8154236 0 8154236 0% /dev/shm
Human-readable sizes
$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 99G 44G 51G 47% /
tmpfs 7.8G 0 7.8G 0% /dev/shm
/dev/sdb1 932G 567G 365G 61% /data
Show filesystem type
$ df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda1 ext4 99G 44G 51G 47% /
tmpfs tmpfs 7.8G 0 7.8G 0% /dev/shm
/dev/sdb1 xfs 932G 567G 365G 61% /data
Check specific path
$ df -h /home
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 200G 89G 111G 45% /home
Show inode usage
$ df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sda1 6553600 234567 6319033 4% /
Only local filesystems
$ df -hl
Show only specific type
$ df -ht ext4
Understanding Output
Filesystem Size Used Avail Use% Mounted on
│ │ │ │ │ │
│ │ │ │ │ └─ Mount point
│ │ │ │ └─ Percentage used
│ │ │ └─ Available space
│ │ └─ Used space
│ └─ Total size
└─ Device or filesystem
Common Patterns
Alert on high usage
$ df -h | awk '$5 > 80 {print $0}'
Check before large operations
$ df -h /backup && tar -czf /backup/data.tar.gz /data
Monitor in watch
$ watch -n 5 'df -h'
Tips
- -h is essential: Raw block counts are hard to read
- Check inodes too: You can run out of inodes before space
- Exclude tmpfs: Use
df -h -x tmpfs -x devtmpfsfor real disks - Use du for directories: df shows filesystems, not folders
