I always receive automatic mails from localhost to /var/spool/mail/root when I work on the shell.Are these log files?How I read and learn meaningful information about terms like as LogWatch,MIME-encapsuled message and SSH etc. Thank you.

Logwatch is pretty cool. It's a perl script that reads from config files. These config files tell logwatch what to look for and whatnot. Usually, logwatch is installed in /etc/log.d. Take a look there and you can tune it to your needs.

-twantrd

[QUOTE]Originally posted by backpacker
I always receive automatic mails from localhost to /var/spool/mail/root when I work on the shell.Are these log files?
[quote]

The logfiles are not the ones in /var/spool/mail/root, this is your standard UNIX mailbox. The messages you receive comes from logwatch, a daemon which watches your logs (logs live in the /var/log directory) and reports any unusual activity there.
There is a specially interesting file: /var/log/messages where all system activity is logged, network, kernel messages... anything (more or less info depending on your settings).

Nice question. Many people forget that UNIX-alike systems has standard built-in documentation for almost anything.

There are 3 standard information sources in UNIX-alike systems :

1. The man pages: These are displayed on a console and contains resumed information about program use and options.
2. The info pages: In a browsable format, has normally more information as the man pages, including tutorials, glossaries and examples
3. The HOWTOs: Mostly extensive tutorials with lots of information and hands-on examples.

man

There are two ways of invoking a man page. The traditional way is using the console or xterm:
man not only includes information about programs, but also about system calls and other stuff.

The more 'modern' way of calling a manpage is using Konqueror and simply typing:
in the URL bar.

info
The Info or texinfo system displays console based browsable documentation (mostly the GNU Toolchain).
The information is structured in "nodes" (chapters), you can access a node by placing your cursor on it and hitting return. Use N to advance 1 node and U to go back.
An easier way to see info files is through the Konqueror web browser with an IOslave:
This lets you use info files in a normal HTML fashion.

HOWTOs
There are two ways of using HOWTOs; you can either install them on your system as a package (every distro has it's own version) stored under /usr/share/doc/HOWTO or you can access them online:
TLDP:HOWTOs

A most valuable source of a large amount of information about just anything on a Linux system is the TLDP: The Linux Documentation Project. Another nice source of information are the manuals every (good) distro includes. So you can find two exceptional manual in SUSE: The administrator and the user handbook, Mandriva also has an extense handbook . Debian based distros such as Debian itself, Ubuntu and Knoppix can use the vast documentation available for Debian, like debhelp ...

And of course; You can ask us ;)