Man cannot find help. Don't forget to use info -- three linux help systems: help, man, info

Man cannot find help. Don't forget to use info -- three linux help systems: help, man, info -- general Linux technology-Linux technology and application information. For more information, see the following. The Linux operating system provides us with very convenient system documentation help information. For example, the "-- help" option, man tool, and info tool documentation. Many beginners are not very familiar with the three concepts of help information. Let's give some targeted explanations.

"-- Help" option

"-- Help" is a tool option. Most GNU tools have this option. The "-- help" option can be used to display information about some tools, such as typing in the command line:

$ Fdisk -- help

"Man" tool

The Man tool displays the content on the system manual page. Most of the content is the explanation of the command. By viewing the man page in the system documentation, you can get more theme information about the program and more features of Linux. Man is a very practical tool. When you use an unfamiliar command, man command is very useful.

To learn more about a tool, you can use the man command followed by the Tool Name.

For example, type:

$ Man fdisk

Press the space key to display the text of the next screen. Press the q key to exit man and return to the shell prompt. You can also use pageup and pagedown for scrolling browsing.

"Info" displays tool information

The Info tool is a menu-based hypertext system developed by the GNU project and released by Linux. The info tool includes some instructions on Linux shell, tools, and GNU project development programs.

In Linux, most software development tools come from the GNU project of the Free Software Foundation. The online documents of these tools and software are in the form of info files. The info program is a GNU hypertext help system.

The info document is generally stored in the/usr/info directory. Run the info command to view the info document.

To run info, enter info at the shell prompt or Press Esc-x and info in GNU emacs.

For example, type:

$ Info fdisk

Press? To list the commands in the info window.

Press the SPACE key to scroll through the menu.

Comparison of the three methods:

The "-- help" option is not an "independent" tool. As a command option, it can be used to modify how a tool or command works. Command Options are usually specified by one or two hyphens followed by one or more letters. The options appear after the called Tool Name and are separated by spaces. Other parameters of the tool are separated by spaces after the options. The "-- help" option is similar to the paging program "| less". It provides quick and efficient help.

Man and info are like two sets. They have an intersection, but compared with man, the info tool displays more complete information about the latest GNU tool. If the summary of a tool on the man page is also described in info, the man page will contain the words "Please refer to more details on the info page. Generally, the information displayed by the man tool is unique and the information displayed by the info tool is a copy of the man page content.