Gives an overview of the file system disk space usage.
# To display all file systems and their disk usage:
df
# To display all file systems and their disk usage in human readable form:
df -h
# To display the file system and its disk usage containing the given file or directory:
df <path/to/file_or_directory>
# To display statistics on the number of free inodes:
df -i
# To display file systems but exclude the specified type:
df -x <squashfs> -x <tmpfs>