umount [options] mountpoint
This command unmounts a mounted drive from the file system. To prevent data
loss, run this command before taking a removable data medium from its drive.
Normally, only root is allowed to run the commands mount and umount. To
enable other users to run these commands, edit the /etc/fstab file to specify
the option user for the respective drive.
18.3.2 System Commands
The following section lists a few of the most important commands needed for retrieving
system information and controlling processes and the network.
System Information
df [options] [directory]
The df (disk free) command, when used without any options, displays information
about the total disk space, the disk space currently in use, and the free space on all
the mounted drives. If a directory is specified, the information is limited to the
drive on which that directory is located.
-h
-T
du [options] [path]
This command, when executed without any parameters, shows the total disk space
occupied by files and subdirectories in the current directory.
-a
-h
-s
370
Installation and Administration
Shows the number of occupied blocks in gigabytes, megabytes, or kilobytes—in
human-readable format
Type of file system (ext2, nfs, etc.)
Displays the size of each individual file
Output in human-readable form
Displays only the calculated total size