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6[NAME]
7df \- report file system disk space usage
8[DESCRIPTION]
9This manual page
10documents the GNU version of
11.BR df .
12.B df
13displays the amount of disk space available on the file system
14containing each file name argument.  If no file name is given, the
15space available on all currently mounted file systems is shown.  Disk
16space is shown in 1K blocks by default, unless the environment
17variable POSIXLY_CORRECT is set, in which case 512-byte blocks are
18used.
19.PP
20If an argument is the absolute file name of a disk device node containing a
21mounted file system,
22.B df
23shows the space available on that file system rather than on the
24file system containing the device node (which is always the root
25file system).  This version of
26.B df
27cannot show the space available on unmounted file systems, because on
28most kinds of systems doing so requires very nonportable intimate
29knowledge of file system structures.
30.SH OPTIONS
31