df

Disk Free - display free disk space.
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.

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

Normally the disk space is printed in units of 1024 bytes, but this
can be overridden.

OPTIONS

 -a
 --all
     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.

 -h
 --human-readable
     Append a size letter such as 'M' for megabytes to each size.
     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.

 -H
 --si
     Append a size letter such as 'M' for megabytes to each size.  (SI
     is the International System of Units, which defines these letters
     as prefixes.)  Powers of 1000 are used, not 1024; 'M' stands for
     1,000,000 bytes.  Use the '-h' or '--human-readable' option if you
     prefer powers of 1024.

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

 -k
 --kilobytes
     Print sizes in 1024-byte blocks, overriding the default block size.

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

 -m
 --megabytes
     Print sizes in megabyte (that is, 1,048,576-byte) blocks.

 --no-sync
     Do not invoke the 'sync' system call before getting any usage data.
     This can make 'df' run significantly faster on systems with many
     disks, but on some systems (notably SunOS) the results can be
     slightly out of date.  This is the default.

 -P
 --portability
     Use the POSIX output format.  This is like the default format
     except that 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.

 --sync
     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
 --type=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.

 -T
 --print-type
     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):

    'nfs'
          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').

    'pcfs'
          An MS-DOS filesystem, usually on a diskette.

 -x FSTYPE
 --exclude-type=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.

 -v
     Ignored; for compatibility with System V versions of 'df'.

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.

Examples

List free disk space:

df -h

Email a disk free space report:

df -h | grep 'File' -A1 | mail -s "Disk space Report" you@example.com

"A prediction is worth twenty explanations" ~ K. Brecher