03-09-2012, 11:59 AM
Duties of the System Administrator
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The Linux System Administrator
Using Linux involves much more than merely sitting down and turning on the
machine. Often you hear talk of a “steep learning curve” but that discouraging
phrase can be misleading. Instead, Linux is quite different from the most popular
commercial operating systems in a number of ways. While it is no more difficult to
learn than other operating systems, it is likely to seem very strange even to the
experienced administrator of other systems. In addition, the sophistication of a
number of parts of the Red Hat distribution has increased by an order of magnitude,
so even an experienced Linux administrator is likely to find much that is new and
unfamiliar. Fortunately, there are new tools designed to make system administration
easier than ever before.
Installing and Configuring Servers
When you hear the word server to describe a computer, you probably think of a
computer that offers some type of service to clients. The server may provide file or
printer sharing, File Transfer Protocol (FTP) or Web access, or e-mail processing
tasks. Don’t think of a server as a standalone workstation; think of it as a computer
that specifically performs these services for many users.
In the Linux world, the word server has a broader meaning than what you might
be used to. For instance, the standard Red Hat graphical user interface (GUI)
requires a graphical layer called XFree86. This is a server. It runs even on a standalone
machine with one user account. It must be configured. (Fortunately, Red Hat
has made this a simple and painless part of installation on all but the most obscure
combinations of video card and monitor; gone are the days of anguish as you configure
a graphical desktop.)
Likewise, printing in Linux takes place only after you configure a print server.
Again, this has become so easy as to be nearly trivial.
In certain areas the client-server nomenclature can be confusing, though. While
you cannot have a graphical desktop without a server, you can have Web access
without a Web server, FTP access without running an FTP server, and e-mail capabilities
without ever starting a mail server. You may well want to use these servers,
all of which are included in Red Hat; then again, maybe not. Whenever a server is
connected to other machines outside your physical control, there are security implications
to consider. You want your users to have easy access to the things they
need but you don’t want to open up the system you’re administering to the whole
wide world.
Installing and Configuring
Application Software
Although it is possible for individual users to install some applications in their
home directories—drive space set aside for their own files and customizations—
these applications are not available to other users without the intervention of the
system administrator. Besides, if an application is to be used by more than one user,
it probably needs to be installed higher up in the Linux file hierarchy, which is a job
that only the system administrator can perform. (The administrator can even decide
which users may use which applications by creating a “group” for that application
and enrolling individual users in that group.)
New software packages might be installed in /opt if they are likely to be
upgraded separately from the Red Hat distribution itself. Doing this makes it simple
to retain the old version until you are certain that the new version works and meets
your expectations. Some packages may need to go in /usr/local or even /usr if
they are upgrades of packages installed as part of Red Hat. (For instance, there are
sometimes security upgrades of existing packages.) The location of the installation
usually matters only if you compile the application from source code; if you use a
Red Hat Package Manager (RPM) application package, it automatically goes where
it should.