Section 24.4. Documentation (Topic 1.108)

24.4. Documentation (Topic 1.108)

24.4.1. Objective 1: Use and Manage Local System Documentation

24.4.1.1. Text and paging

• In the context of Linux systems, plain text means files or streams of both printable characters and control characters, using a standard encoding scheme such as ASCII.

• Differentiating text from nontext isn't obvious, but the file command examines a file given as its argument and offers a response that indicates the file type.

• A pager is a program intended to offer a quick and simple interface for viewing text files, one screen at a time.

• more is a popular pager available on most Unix systems.

• less is a full-featured text pager, which emulates more and offers significant advantages. Common less commands are listed in Table 24-1.

  Table 24-1. Common less commands

  less command	Description
  Space	Scroll forward one screen.
  D	Scroll forward one-half screen.
  Return	Scroll forward one line.
  B	Scroll backward one screen.
  U	Scroll backward one-half screen.
  Y	Scroll backward one line.
  g	Go to the beginning of the text (could be slow with large amounts of text).
  G	Go to the end of the text (could be slow with large amounts of text).
  /pattern	Search forward for pattern, which can be a regular expression.
  ?pattern	Search backward for pattern, which can be a regular expression.
  H	Display a help screen.
  :n	Display next file from command line (two-character command).
  :p	Display previous file from command line (two-character command).

  
  

• A pager such as less is used by the man facility.

24.4.1.2. The man facility

• A manpage exists for most commands and is viewed using man:

  
  

  man [section] command

  Format and display manpages from the manual section based on the topic of command using a pager.

• Manpages are usually found in the /usr/man directory, but they can also be found elsewhere in the filesystem. The manpage location can be found in /etc/man.config, along with the paging program to use and other information about the manpages.

24.4.1.3. /usr/doc

• Many documents for Linux systems are available in /usr/doc. Included here are package-related documents, FAQs, HOWTOs, and so on.

24.4.1.4. The info facility

• The Free Software Foundation provides the info documentation format.

• GNU software comes with info documentation.

• The documentation is viewed with the info command, which displays a full-screen editor-like paging system. Common info commands are listed in Table 16-3.

24.4.2. Objective 2: Find Linux Documentation on the Internet

24.4.2.1. Linux Documentation Project

• A loosely knit team of writers, proofreaders, and editors who work together to create the definitive set of documentation for Linux. The Linux Documentation Project can be found online at http://www.tldp.org.

• The LDP has a wide range of documents, from complete books to personal accounts of problem-solving techniques.

24.4.2.2. Other sources

• Many Usenet newsgroups , such as comp.os.linux, comp.os.linux.advocacy, comp.os.linux.development, and others, are dedicated to Linux.

• Mailing lists offered by many Linux groups serve to keep members informed through email distribution of information.

24.4.3. Objective 5: Notify Users on System-related Issues

24.4.3.1. /etc/issue

• The /etc/issue file is responsible for the text that appears after a login at the system console.

24.4.3.2. /etc/issue.net

• The /etc/issue.net contains the text that appears when you log in remotely with Telnet.

24.4.3.3. /etc/motd

• The /etc/motd file is intended to be used as the message of the day. Its content is shown after a successful system login.