Red Hat ENTERPRISE LINUX 4 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual page 109

Chapter 5. Managing Storage
point. When a file system is mounted, that file system is made available as a set of subdirectories
under the specified mount point.
This apparent shortcoming is actually a strength. It means that seamless expansion of a Linux file
system is possible, with every directory capable of acting as a mount point for additional disk space.
As an example, assume a Red Hat Enterprise Linux system contained a directory
directory; the full path to the directory would be
that is to be mounted, and that the partition's mount point is to be
the name of
bar.txt
file with the following full file specification:
/foo/bar.txt
In other words, once this partition has been mounted, any file that is read or written anywhere under
the directory will be read from or written to that partition.
/foo/
A commonly-used mount point on many Red Hat Enterprise Linux systems is
because the login directories for all user accounts are normally located under
is used as a mount point, all users' files are written to a dedicated partition and will not fill up the
operating system's file system.
Tip
Since a mount point is just an ordinary directory, it is possible to write files into a directory that is later
used as a mount point. If this happens, what happens to the files that were in the directory originally?
For as long as a partition is mounted on the directory, the files are not accessible (the mounted file
system appears in place of the directory's contents). However, the files will not be harmed and can
be accessed after the partition is unmounted.
5.9.3.2. Seeing What is Mounted
In addition to mounting and unmounting disk space, it is possible to see what is mounted. There are
several different ways of doing this:
Viewing
•
/etc/mtab
Viewing
• /proc/mounts
Issuing the command
• df
5.9.3.2.1. Viewing
/etc/mtab
The file
/etc/mtab
mounted or unmounted. Here is a sample
/dev/sda3 / ext3 rw 0 0
none /proc proc rw 0 0
usbdevfs /proc/bus/usb usbdevfs rw 0 0
/dev/sda1 /boot ext3 rw 0 0
none /dev/pts devpts rw,gid=5,mode=620 0 0
/dev/sda4 /home ext3 rw 0 0
none /dev/shm tmpfs rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
in its top-level directory, after the partition was mounted you could access the
is a normal file that is updated by the
/etc/mtab
. Next, assume that this system has a partition
/foo/
/foo/
program whenever file systems are
mount
:
in its root
foo
. If that partition had a file by
— that is
/home/
. If
/home/
97
/home/