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14.1 df: Report filesystem disk space usage

df reports the amount of disk space used and available on filesystems. Synopsis:

df [option]... [file]...

With no arguments, df reports the space used and available on all currently mounted filesystems (of all types). Otherwise, df reports on the filesystem containing each argument file.

Normally the disk space is printed in units of 1024 bytes, but this can be overridden (see section 2.2 Block size). Non-integer quantities are rounded up to the next higher unit.

If an argument file is a disk device file containing a mounted filesystem, df shows the space available on that filesystem rather than on the filesystem containing the device node (i.e., the root filesystem). GNU df does not attempt to determine the disk usage on unmounted filesystems, because on most kinds of systems doing so requires extremely nonportable intimate knowledge of filesystem structures.

The program accepts the following options. Also see 2. Common options.

Include in the listing filesystems that have a size of 0 blocks, which are omitted by default. Such filesystems are typically special-purpose pseudo-filesystems, such as automounter entries. Also, filesystems of type "ignore" or "auto", supported by some operating systems, are only included if this option is specified.

`-B size'
Scale sizes by size before printing them (see section 2.2 Block size). For example, `-BG' prints sizes in units of 1,073,741,824 bytes.

Append a size letter to each size, such as `M' for mebibytes. Powers of 1024 are used, not 1000; `M' stands for 1,048,576 bytes. Use the `-H' or `--si' option if you prefer powers of 1000.

Append an SI-style abbreviation to each size, such as `MB' for megabytes. Powers of 1000 are used, not 1024; `MB' stands for 1,000,000 bytes. Use the `-h' or `--human-readable' option if you prefer powers of 1024.

List inode usage information instead of block usage. An inode (short for index node) contains information about a file such as its owner, permissions, timestamps, and location on the disk.

Print sizes in 1024-byte blocks, overriding the default block size (see section 2.2 Block size). This option is equivalent to `--block-size=1K'.

Limit the listing to local filesystems. By default, remote filesystems are also listed.

Do not invoke the sync system call before getting any usage data. This may make df run significantly faster on systems with many disks, but on some systems (notably SunOS) the results may be slightly out of date. This is the default.

Use the POSIX output format. This is like the default format except for the following:

  1. The information about each filesystem is always printed on exactly one line; a mount device is never put on a line by itself. This means that if the mount device name is more than 20 characters long (e.g., for some network mounts), the columns are misaligned.

  2. The labels in the header output line are changed to conform to POSIX.

Invoke the sync system call before getting any usage data. On some systems (notably SunOS), doing this yields more up to date results, but in general this option makes df much slower, especially when there are many or very busy filesystems.

`-t fstype'
Limit the listing to filesystems of type fstype. Multiple filesystem types can be specified by giving multiple `-t' options. By default, nothing is omitted.

Print each filesystem's type. The types printed here are the same ones you can include or exclude with `-t' and `-x'. The particular types printed are whatever is supported by the system. Here are some of the common names (this list is certainly not exhaustive):

An NFS filesystem, i.e., one mounted over a network from another machine. This is the one type name which seems to be used uniformly by all systems.

`4.2, ufs, efs...'
A filesystem on a locally-mounted hard disk. (The system might even support more than one type here; Linux does.)

`hsfs, cdfs'
A filesystem on a CD-ROM drive. HP-UX uses `cdfs', most other systems use `hsfs' (`hs' for "High Sierra").

An MS-DOS filesystem, usually on a diskette.

`-x fstype'
Limit the listing to filesystems not of type fstype. Multiple filesystem types can be eliminated by giving multiple `-x' options. By default, no filesystem types are omitted.

Ignored; for compatibility with System V versions of df.

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