> For the complete documentation index, see [llms.txt](https://olb.gitbook.io/linux-essentials-certification/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://olb.gitbook.io/linux-essentials-certification/2.finding_your_way_on_linux/2.2-cli_help.md).

# 2.2 CLI Help

**Weight 2**\
Key knowledge areas

* Man pages
* Info pages

Partial list of the used files, terms and utilities

* man
* info
* /usr/share/doc/
* locate

***

* various tools for help `man`, `help`, `info`, `/usr/share/doc/`

## Built-in Help

* `-- help` not for all commands and brief instructions

## Man Pages

* divided in 11 sections
* organized in 8 categories
* use less by `default`
* search with `/` + `n` for next matches
* `man -k them` search theme in all man pages = a propos
* `man -w command` display location of the man page
* Section & Description
  * NAME : Command name and brief description
  * SYNOPSIS : Description of the command’s syntax
  * DESCRIPTION : Description of the effects of the command
  * OPTIONS : Available options
  * ARGUMENTS : Available arguments
  * FILES : Auxiliary files
  * EXAMPLES : A sample of the command line
  * SEE ALSO : Cross-references to the related topics
  * DIAGNOSTICS : Warning and Error messages
  * COPYRIGHT : Author(s) of the command
  * BUGS : Any known limitations of the command
* Category Description
  * 1 User command
  * 2 System calls
  * 3 Functions of the C library
  * 4 Drivers and device files
  * 5 Configuration files and file formats
  * 6 Games
  * 7 Miscellaneous
  * 8 System administrator commands
  * 9 Kernel functions (not standard)

## Info Pages

* contains hypertext
* different nodes within a tree
* press enter to follow link
* `?` to search

## /usr/share/doc/ directory

* name of directory = package name
* README files

## Locating files

### locate

* `locate filename`
* support wildcards and regular expressions
* run `updatedb` to update database

### find

* `find . -name *filename*`

## Command used

* **man** Display a man page.
* **info** Display an info page.
* **locate** Search the locate database for files with a specific name.
* **find** Search the file system for names matching a set of selection criteria.
* **updatedb** Update the locate database.