What Is the df Command in Linux?¶
Introduction¶
The df command reports filesystem space usage. It is useful for beginners, Linux administrators, DevOps engineers, and RHCSA students because it solves practical terminal tasks.
What the Command Does¶
Use df to work with the specific Linux object it manages. Before changing anything, identify the target and run a read-only check when possible.
Basic Syntax¶
df OPTIONS PATH
The syntax includes the command, any options, and the target object.
Common Options¶
-h: show human-readable sizes.-T: show filesystem type.-i: show inode usage.
Practical Examples¶
df
df -h
df -h /var
df -Th
Verification command:
findmnt /var
Example output:
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 50G 18G 33G 36% /
When to Use This Command¶
Use df when you need to know whether a filesystem is full or how much capacity remains on a mounted filesystem.
Common Mistakes¶
- Confusing filesystem usage from df with directory size from du.
- Ignoring inode exhaustion when block space is still available.
- Checking the wrong mount point after bind mounts or separate filesystems.
Quick Reference¶
df
df -h
findmnt /var
Related Guides¶
Summary¶
The df command is safest when you understand the target, choose the right option, and verify the result with a separate command.