df : report file system disk space usage
[SYNOPSIS] df OPTION DIRECTORY
OPTION
-a include dummy file systems
-B, --block-size=SIZE use SIZE-byte blocks
--direct show statistics for a file instead of mount point
--total produce a grand total
-h print sizes in human readable format (e.g., 1K 234M 2G)
-H likewise, but use powers of 1000 not 1024
-i list inode information instead of block usage
-k print sizes in human readable format (e.g., 1K 234M 2G)
-l limit listing to local file systems
--no-sync do not invoke sync before getting usage info (default)
-P use the POSIX output format
--sync invoke sync before getting usage info
-t, --type=TYPE limit listing to file systems of type TYPE
-T print file system type
-x, --exclude-type=TYPE limit listing to file systems not of type TYPE
--help display help and exit
--version output version information and exit