Cheatsheet & Examples: df
Basic Disk Usage Report
Example Usage:
df
What it does: Displays the amount of disk space used and available on all mounted filesystems, using default units (blocks) and summarizing the data.
Command-line Arguments Explained:
- None: No arguments provided, so
dfdefaults to showing disk usage for all filesystems in blocks.
Human-Readable Disk Usage
Example Usage:
df -h
What it does: Shows disk usage in a human-readable format, using units like KB, MB, and GB instead of raw block counts.
Command-line Arguments Explained:
-h: Enables human-readable output, converting block sizes to easily understandable units.
Show All Filesystems
Example Usage:
df -a
What it does:
Displays disk usage for all filesystems, including virtual ones like tmpfs or proc, which are usually excluded by default.
Command-line Arguments Explained:
-a: Includes all filesystems in the output, even those that are typically not shown (e.g., virtual or special-purpose filesystems).
Disk Usage in Specific Units
Example Usage:
df -k or df -m
What it does:
Displays disk usage in kilobytes (-k) or megabytes (-m) instead of the default block size.
Command-line Arguments Explained:
-k: Uses kilobytes as the unit for display.-m: Uses megabytes as the unit for display.
Filter by Filesystem Type
Example Usage:
df -t ext4
What it does:
Shows disk usage information only for filesystems of the specified type (e.g., ext4).
Command-line Arguments Explained:
-t: Filters the output to display only filesystems of the given type (e.g.,ext4,xfs,ntfs).
Exclude Specific Filesystem Types
Example Usage:
df --exclude-type=tmpfs
What it does:
Excludes filesystems of the specified type (e.g., tmpfs) from the disk usage report.
Command-line Arguments Explained:
--exclude-type: Filters out filesystems of the given type from the output.
Inode Usage Statistics
Example Usage:
df -i
What it does: Displays information about inode usage rather than block usage, showing how many inodes are used and available.
Command-line Arguments Explained:
-i: Shows inodes (file metadata) usage instead of disk space usage.
Custom Output Fields
Example Usage:
df --output=source,fstype,size,used,avail
What it does: Customizes the output to show specific fields (e.g., device source, filesystem type, size, used space, available space).
Command-line Arguments Explained:
--output: Specifies which fields to display in the output. Available fields includesource,fstype,size,used,avail,capacity,mountpoint, and more.
Disk Usage Summary
Example Usage:
df --summarize
What it does: Provides a summary line at the end of the output, showing the total used and available space across all mounted filesystems.
Command-line Arguments Explained:
--summarize: Adds a summary line to the output, summarizing disk usage for all filesystems.
Disk Usage with Specified Block Size
Example Usage:
df --block-size=1M
What it does: Displays disk usage in the specified block size (e.g., megabytes) instead of the default.
Command-line Arguments Explained:
--block-size: Sets the block size for display. Valid values include1K,1M,1G(kilobytes, megabytes, gigabytes), or any numeric multiplier.
Help and Usage Instructions
Example Usage:
df --help
What it does:
Displays a help message with usage instructions and available options for the df command.
Command-line Arguments Explained:
--help: Shows a summary of how to usedfand lists its available options.
Version Information
Example Usage:
df --version
What it does:
Outputs the version of the df utility installed on the system.
Command-line Arguments Explained:
--version: Displays the version number ofdf, confirming the implementation (GNU coreutils, macOS, etc.).
