Linux Know-How provides a collection of introductory texts on often needed Linux skills.

Help commands

any_command --help |more

Display a brief help on a command (works with most commands). For example, try cp --help |more. "--help" works similar to DOS "/h" switch. The "more" pipe is needed when the output is longer than one screen.

man topic

Display the contents of the system manual pages (help) on the topic. Press "q" to quit the viewer. Try man man if you need any advanced options. The command info topic works similar to man topic, yet it may contain more up-to-date information. Manual pages can be hard to read--they were written for UNIX programmers. Try any_command --help for a brief, easier to digest help on a command. Some programs also come with README or other info files--have a look to the directory /usr/share/doc. To display manual page from a specific section, I may use something like: man 3 exit (this displays an info on the command exit from section 3 of the manual pages) or man -a exit (this displays man pages for exit from all sections). The man sections are: Section 1-User Commands, Section 2-System Calls, Section 3-Subroutines, Section 4-Devices, Section 5-File Formats, Section 6-Games, Section 7-Miscellaneous, Section 8-System Administration, Section 9, Section n-New. To print a manual page, I use: man topic | col -b | lpr (the option col -b removes any backspace or other characters that could make the printed manpage difficult to read).

info topic

Display the contents of the info on a particular command. info is a replacement for man pages so it contains the most recent updates to the system documentation. Use <Space> and <BkSpace> to move around or you may get confused. Press "q" to quit. A replacement for the somewhat confusing info browsing system might be pinfo - try if you like it any better.

apropos topic

Give me the list of the commands that have something to do with my topic.

whatis topic

Give me a short list of commands matching my topic. whatis is similar to apropos (see the command above)--they both use the same database. But whatis searches keywords, while apropos also searches the descriptions of the keywords.

help command

Display brief info on a bash (shell) built-in command. Using help with no command prints the list of all bash built-in commands. The shortest list of bash built-in commands would probably include: alias, bg, cd, echo, exit, export, fg, help, history, jobs, kill, logout, pwd, set, source, ulimit, umask, unalias, unset.

kdehelpcenter &

(in X-terminal). Browse the whole system help using the graphical KDE help navigator. Normally, KDE help is invoked by pressing the appropriate icon on the KDE control panel. Use gnome-help-browser for the GNOME equivalent. (The older KDE versions used kdehelp& instead of kdehelpcenter&).

Last Update: 2010-12-16