df Troubleshooting Disk Full in Linux¶
Introduction¶
Advanced df usage helps when the basic form is not enough. This article focuses on realistic command patterns that are useful during administration and troubleshooting.
When You Need Advanced Usage¶
Use df when you need to know whether a filesystem is full or how much capacity remains on a mounted filesystem. Advanced usage is most useful when you need to narrow scope, work on multiple targets, or diagnose why the first command did not answer the question.
Practical Examples¶
Inspect first:
findmnt /var
Run a focused command:
df -h /var
Use a real-world pattern:
df -Th
Troubleshooting¶
If df does not give the expected result, verify the target first with findmnt /var. Then check permissions, paths, service state, network reachability, package repositories, or process state depending on what the command manages.
Example output:
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 50G 18G 33G 36% /
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.
Safety Notes¶
Use a preview, backup, dry run, read-only command, or smaller test target before applying broad, recursive, destructive, or remote operations.
Related Guides¶
Summary¶
Advanced df usage should still be controlled. Build the command step by step and verify the result separately.