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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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df [options] [name]

Report the amount of free disk space available on all mounted filesystems or on the given name. (df cannot report on unmounted filesystems.) Disk space is shown in 1 KB blocks (default) or 512-byte blocks (if the environment variable POSIXLY_CORRECT is set). name can be a device name (e.g., /dev/hd*), the directory name of a mounting point (e.g., /usr), or a directory name (in which case df reports on the entire filesystem in which that directory is mounted).


-a, --all

Include empty filesystems (those with 0 blocks).


Show space as n-byte blocks.

-h, --human-readable

Print sizes in a format friendly to human readers (e.g., 1.9G instead of 1967156).

-H, --si

Like -h, but show as power of 1000 rather than 1024.

-i, --inodes

Report free, used, and percent-used inodes.

-k, --kilobytes

Print sizes in kilobytes.

-l, --local

Show local filesystems only.

-m, --megabytes

Print sizes in megabytes.


Show results without invoking sync first (i.e., without flushing the buffers). This is the default.

-P, --portability

Use POSIX output format (i.e., print information about each filesystem on exactly one line).


Invoke sync (flush buffers) before getting and showing sizes.

-t type, --type=type

Show only type filesystems.

-T, --print-type

Print the type of each filesystem in addition to the sizes.

-x type, --exclude-type=type

Show only filesystems that are not of type type.


Print help message and then exit.


Print the version and then exit.

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