When you are looking for general help on commands and error messages, the best place to start is right on your system. There are several different sources of information at your fingertips:

• Man Pages -- Authoritative reference material for commands, file formats, and system calls.

• Package Documentation -- Many packages include additional documentation; RPM can help you find it.

• HOWTOs and FAQs -- Helpful information from the Linux Documentation Project.

• The locate Command -- A command that can help bridge the gap between a command and its documentation.

• info Pages -- Hypertext documentation without the Web.

Let's take a look at each information source.

Almost every command on your system has an associated ``man'' page. This is documentation that you can get to instantly should you have questions or problems. For example, if you were having trouble with the ls command, you could use man to get more information by entering man ls. This will bring up the man page for ls.

The man page is viewed through the less program (which makes it easy to page forward and backward screen by screen), so all of the options to less will work while in a man page. The more important keystrokes for less are:

• [q] to quit
• [Enter] to page down line by line
• [Space] to page down page by page
• [b] to page back up by one page
• [/] followed by a string and [Enter] to search for a string
• [n] to find the next occurrence of the previous search

If you do have a postscript printer, you will probably want to print with:

man -t COMMAND | lpr

In both of those commands substitute ``COMMAND'' for the command you are trying to get help for.

This is also the order in which the sections are searched. This can be important; here's an example:

Man pages provide a great deal of information in very little space. Because of this, they can be difficult to read. Here's a quick overview of the major sections in most man pages:

• Name -- The name of the program or programs documented in the man page. There may be more than one name, if the programs are closely related.

• Synopsis -- An overview of the program's command syntax, showing all options and arguments.

• Description -- A short description of the program's function.

• Options -- A list of all options, with a short description of each (often combined with the previous section).

• See Also -- If present, lists the names of other programs that are related in some way to this program.

• Files -- If present, contains a list of files that are used and/or modified by the program.

• History -- If present, indicates important milestones in the program's development.

• Authors -- The people that wrote the program.

If you are new to Linux, don't expect to be able to use man pages as tutorials; they are meant as concise reference material. Trying to learn about Linux using the man pages is similar to trying to learn how to speak English from reading a dictionary. But there are other sources of information that may be more useful to those people just starting out with Linux; let's continue our search for documentation...

Many packages have README files and other documentation as part of the source package. Packages built for Red Hat Linux define a standard place to install those documents so that you don't have to search through the sources to find the documents. Every package containing documentation (other than man pages, and files that need to be in specific locations) places their documentation in a subdirectory of /usr/doc.

The name of the subdirectory depends on the package name and version number. For example, For example, the tin package might be at version 1.22. Therefore, the path to its documentation would be /usr/doc/tin-1.22.

When you don't know the full name of a command or file, but need to find it, you can usually find it with locate. locate uses a database to find all files on your system. Normally, this database gets built from a cron job every night. This won't happen, however, if your machine isn't booted into Linux all the time. So, if that is the case, you may occasionally want to run the following command:

/etc/cron.daily/updatedb.cron

You will need to be root on your system when doing that. That will allow locate to work properly.

So, if you know you need to find all the ``finger'' files, you could run:

locate finger

It should return something like:

/usr/bin/finger
/usr/lib/irc/script/finger
/usr/man/man1/finger.1
/usr/man/man8/in.fingerd.8
/usr/sbin/in.fingerd

One thing to note, however, is that locate not only returns hits based on file name, but also on path name. So if you have a /home/djb/finger/ directory on your system, it would get returned along with all files in the directory.

While man is the most ubiquitous documentation format, info is much more powerful. It provides hypertext links to make reading large documents much easier and many features for the documentation writer. There are some very complete info documents on various aspects of Red Hat (especially the portions from the GNU project).

To read info documentation, use the info program without any arguments. It will present you with a list of available documentation. If it can't find something, it's probably because you don't have the package installed that includes that documentation. Install it with RPM and try again.