Page 155 - DCAP403_Operating System

Operating System

Notes On standalone machines, the following file systems reside on the associated devices by default:

/File System /Device
/dev/hd1 /home
/dev/hd2 /usr
/dev/hd3 /tmp
/dev/hd4 /(root)
/dev/hd9var /var
/proc /proc
/dev/hd10opt /opt

The file tree has the following characteristics:
1. Files that can be shared by machines of the same hardware architecture are located in
the /usr fi le system.
2. Variable per-client files, for example, spool and mail files, are located in the /var fi le

system.

3. The /(root) file system contains files and directories critical for system operation.
Example: It contains

(a) A device directory (/dev)

(b) Mount points where file systems can be mounted onto the root file system, for

example, /mnt

4. The /home file system is the mount point for users’ home directories.

5. For servers, the /export directory contains paging-space files, per-client (unshared) root fi le
systems, dump, home, and /usr/share directories for diskless clients, as well as exported
/usr directories.

6. The/proc file system contains information about the state of processes and threads in the
system.
7. The/opt file system contains optional software, such as applications.

The following list provides information about the contents of some of the subdirectories
of the /(root) fi le system.

/bin Symbolic link to the /usr/bin directory.

/dev Contains device nodes for special files for local devices. The /dev directory contains special fi les
for tape drives, printers, disk partitions, and terminals.
/etc Contains confi guration files that vary for each machine. Examples include:

1. /etc/hosts
2. /etc/passwd

/export Contains the directories and files on a server that are for remote clients.

/home Serves as a mount point for a file system containing user home directories. The /home fi le
system contains per-user files and directories.

In a standalone machine, a separate local file system is mounted over the /home directory. In

a network, a server might contain user files that should be accessible from several machines. In
this case, the server’s copy of the /home directory is remotely mounted onto a local /home fi le
system.
/lib Symbolic link to the /usr/lib directory, which contains architecture-independent libraries with
names in the form lib*.a.
Contd....

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