Linux Help

Posted: September 22, 2010 in REDHAT 5 LinUX
Sources of help include:

  1. Man pages – Stands for manual pages and are available on your system by invoking the word “man” followed by the subject, you need help for. An example is “man inetd” for information about the inetd internet super daemon program.
  2. Info – Info pages are meant as a replacement for man pages but are harder to use which is why man pages are still popular.
  3. Howtos – Howtos are written about various functional areas and Linux programs. They are likely to be available on your system in the /usr/doc/HOWTO directory. They are also available at various websites which can be accessed from the CTDP Linux Weblinks section.
  4. GNU manuals – Accessible through the GNU website which you can find in the the CTDP Linux Weblinks Documentation section.
  5. Package documentation – Documentation that comes with individual packages, usually found with the package or in the /usr/doc or /usr/local directory.
  6. Other LDP documents – There are many excellent Linux documents written in book form provided by The Linux Documentation Project which are available at their website. Their website may be accessed from the CTDP Linux Weblinks section. Many of these documents include subjects about Linux system administration, the Linux kernel, security and more.
  7. Independent documents and resources – There are many excellent independently written documents. Watch the Linux Weblinks section for information on these types of resources. These resources are added as they are located or suggested by CTDP members or the public.

Man Pages

Man pages general are written to describe programs, configuration files, functions and more areas of the system. They are organized into numbered sections covering various subject areas as follows:

  1. User commands that may be started by everyone.
  2. System calls, functions provided by the kernel.
  3. Subroutines, which are, library functions.
  4. Devices, which are, special files in the /dev directory needed to access items like com ports and disk drives among many other things.
  5. File format descriptions, such as configuration files and files like /etc/passwd.
  6. Games.
  7. Miscellaneous, such as macro packages, standard methods.
  8. System administration tools for the root user.
  9. More kernel routine documentation specifically for linux.

There may be other non numbered sections:

  • n – New documentation, that may be moved to a more appropriate section.
  • o – Old documentation, that may be kept for a grace period.
  • l – Local documentation referring to this particular system.

When referenced in documentation, man pages are many times referred to by section. For example see the man page on inetd(8). You normally don’t need to do anything special to see the page in section 8 except type “man inetd”. The syntax for using man pages is “man command”, where “command” is the name of the command or item you want help for. Sometimes a given name is in more than one section. For instance the name crontab is a configuration file and a utility used to perform configuration. There is a man page for this in sections 1 and 5. If “man crontab” is typed the file in section one will be shown. In this case you will need to type the section number as follows:

man 5 crontab

Once you are in a man page, type [space] to see the next page, and type “Q” anytime to quit

Searching pages:

You can use a keyword function in man. To find commands that deal with DNS, type “man -k dns”. A list of all commands system calls and other items that have the word “dns” in their name or short description is given. Entering “man -k dns| grep domain” will search the man pages for occurrences of “dns” and “domain”. Another command equivalent to using the “man -k is the apropos command. To search on a particular subject in the man page library type “apropos subject”. A list of all man pages with the associated subject in its description will be displayed. This information is kept in the apropos database which is updated weekly by cron. See the section on cron or type “man apropos” or “man whatis” for more information.

To print a man page type “man name | lpr -P”. You must have your printer set up for this to work.

Info Pages

Much documentation is included as info pages. Many times the same documentation is included in man pages, but sometimes information is included in infopages that is not in man pages. I don’t like info pages since you need to remember many different key commands to navigate through them. There is a tutorial in the info pages that you can use to learn the commands. I recommend that before using info pages, you do at least a quick tour by taking the tutorial. Take notes and keep them handy when using the info pages. You may use the info pages by typing “info command” where command is the name of the command you need information about. To begin the tutorial, type “info”, and look for the help section. Some of the basic info commands are listed below.

h Take the help tutorial
<SPC> To move down (see more text) on a screen
<del> or Backspace To page up the screen
b To move to the top of a screen
n To move to the next node (text on a particular topic)
p To move to the previous node
d To move to the main directory node
l To move to the last node you were at. Retraces where you were.
<CTRL>L Refresh the screen
m Show a menu of nodes you can move to
<CTRL>g Cancel menu selection
name Type node name or Ctrl-g to cancel after typing “m” for menu
u To move back to the menu you were at. Use this command after making a menu selection to get back to the last menu from which you made a selection.
? Show available commands.

Howto Documents and GNU manuals

Along with the man pages there is much Linux documentation contained in the various howto files and GNU documents written by the Linux community. There are many links on the web to help you find these sources of documentation. The easiest way to find these documents is to link to the websites that have them in the Linux, Weblinks, Documentation section of this website. Most of the how to documents should be on your system in the directory /usr/doc/HOWTO. They are in text format and can be read by the program “less” or any text editor.

Package Documentation

Linux is generally made up of many packages. Each package deals with certain functionality of Linux, but may have several commands. For instance, the etherboot package has a purpose of allowing users to set up remote machines for booting using a Linux server. This package has several binary programs used to perform this function. Most packages contain various text files or html or dvi files that contain further documentation about the package and their various commands. Most package documentation is in the directory “/usr/doc” or “/usr/local” under the specific package name. There are also various important manuals which may have come with your distribution. These manuals may be in postscript format. From an X session if you locate these files, you can double click on them to read them in postscript. The names of some of these manuals are:

  1. Bash Reference Manual
  2. LILO User’s Guide
  3. LILO Technical Overview
  4. Name Server Operations Guide for BIND
  5. IP Command Reference
  6. IPv6 Flow Labels in Linux-2.2
  7. Tunnels over IP in Linux-2.2
  8. IP Chains Quick Reference
  9. Sendmail Installation and Operations Guide
  10. Sendmail – An Internetwork Mail Router
  11. mgetty+sendfax
  12. Automated System Monitoring and Notification with SWATCH
  13. SGML-Tools User’s Guide
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