Although this command is known by almost all of the developer, anyway I record it just to remind that it is a very important to display the amount of available disk space, whether there is a disk mounted … blabla, ok stop, you gonna to get which command it is, here is a copy from its manuel :
df – report file system disk space usage (disk free)
df [OPTION]… [FILE]…
This manual page documents the GNU version of df. df displays the amount of disk space available on the file system containing
each file name argument. If no file name is given, the space available on all currently mounted file systems is shown. Disk
space is shown in 1K blocks by default, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are
If an argument is the absolute file name of a disk device node containing a mounted file system, df shows the space available on
that file system rather than on the file system containing the device node (which is always the root file system). This version
of df cannot show the space available on unmounted file systems, because on most kinds of systems doing so requires very non‐
portable intimate knowledge of file system structures.
Show information about the file system on which each FILE resides, or all file systems by default.
Mandatory arguments to long options are mandatory for short options too.
include dummy file systems
(dummy file systems : filesystems that have a size of 0 blocks, which are omitted by default.)
scale sizes by SIZE before printing them. E.g., `-BM’ prints sizes in units of 1,048,576 bytes. See SIZE format below.
produce a grand total
-h, –human-readable (used more frequently because I am a human)
print sizes in human readable format (e.g., 1K 234M 2G)
likewise, but use powers of 1000 not 1024
list inode information instead of block usage
-k like –block-size=1K
limit listing to local file systems
do not invoke sync before getting usage info (default)
use the POSIX output format
–sync invoke sync before getting usage info
-t, –type=TYPE (useful if you know the type of your filesystem which u want to find)
limit listing to file systems of type TYPE
-T, –print-type (display the column Type additionally)
print file system type
-x, –exclude-type=TYPE (equivalent to NOT -t)
limit listing to file systems not of type TYPE
–help display this help and exit
output version information and exit
Display values are in units of the first available SIZE from –block-size, and the DF_BLOCK_SIZE, BLOCK_SIZE and BLOCKSIZE envi‐
ronment variables. Otherwise, units default to 1024 bytes (or 512 if POSIXLY_CORRECT is set).
SIZE may be (or may be an integer optionally followed by) one of following: KB 1000, K 1024, MB 1000*1000, M 1024*1024, and so on for G, T, P, E, Z, Y.