mounted by other users, enter the option user in the appropriate line in the /etc/
fstab le (separated by commas) and save this change. Further information is
available in the mount(1) man page.
umount [options] mountpoint
This command unmounts a mounted drive from the le 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 le to specify the option
user for the relevant drive.
17.12.2 System Commands
The following section lists a few of the most important commands needed for retriev-
ing system information and controlling processes and the network.
17.12.2.1 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 specied, the information is limited to the
drive on which that directory is located.
-h
Shows the number of occupied blocks in gigabytes, megabytes, or kilobytes—in
human-readable format
-T
Type of le system (ext2, nfs, etc.)
du [options] [path]
This command, when executed without any parameters, shows the total disk
space occupied by les and subdirectories in the current directory.
-a
Displays the size of each individual le
-h
Output in human-readable form
-s
Displays only the calculated total size
free [options]
The command free displays information about RAM and swap space usage,
showing the total and the used amount in both categories. See Section “The free
Command” (Chapter 11, Special System Features, ↑Reference) for more informa-
tion.
220 Start-Up
