Linux tutorial-online help

Article title: Linux tutorial-online help. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
The TurboLinux system provides a large number of commands and many utility software. due to the length of this book, it mainly introduces some common commands and practical software of TurboLinux. Readers can use the online help manual provided by the system to obtain more information.
　　
The online manual of TurboLinux contains a large amount of available information, which is divided into several sections based on the content. Almost every command is described in the Linux Online Help Manual. Therefore, if you do not know much about a command on Linux, use the online help command.
　　
This chapter describes several common online help commands. Including:
　　
How to use man to query each command
　　
Help query Shell commands
　　
Whereis query the location of a command
　　
Locate query the location of a file
　　
Man command
　　
This command should be available on every Linux system. It is formatted and displays the online manual page. Generally, if you enter the name (such as ls) of the command you want to obtain after the command man, man will list a complete description, the content includes the command syntax, meaning of each option, and related commands.
　　
The command is generally in the following format:
　　
Man [option] command name
　　
The meanings of the options in the command are as follows:
　　
-M path specifies the path for searching man manual pages. Generally, this path is preset by the environment variable MANPATH. if another path is specified on the command line, the MANPATH setting is overwritten.
　　
-P command specifies the paging program used./usr/bin/less? is used by default? Is, which is preset in the environment variable MANPAGER.
　　
-S section because a command name may have many categories, the categories are listed as follows:
　　
Chapter description
　　
1. commands of general users
　　
2. commands called by the system
　　
3 C language function library commands
　　
4. explanations of drivers and system devices
　　
5. description of the configuration file
　　
6. game program commands
　　
7. other software or program commands
　　
Commands for system maintenance
　　
-A shows all the manual pages instead of the first one.
　　
-D is mainly used during the check. if you add a new file, you can use this option to check for errors. This option does not list the file content.
　　
-F only displays the command function, but not the detailed description file.
　　
-P string indicates the sequence of the pre-processed programs to run. the following items are displayed:
　　
E eqn t tbl
　　
G grap r refer
　　
P pic v vgrind
　　
-W: The manual page is not displayed. only the location of the file to be formatted and displayed is displayed.
　　
For example, view how to use the cd command.
　　
$ Man cd
　　
Cd (n) Tcl Built-In Commands cd (n)
　　
_________________________________________________________________
　　
NAME
　　
Cd-Change working directory
　　
SYNOPSIS
　　
Cd? DirName?
　　
_________________________________________________________________
　　
DESCRIPTION
　　
Change the current working directory to dirName, or to
　　
Home directory (as specified in the HOME environment vari-
　　
Able) if dirName is not given. Returns an empty string.
　　
KEYWORDS
　　
Working directory
　　
Tcl 1
　　
(END)
　　
You can press q to exit the man command.
　　
Help command
　　
The help command is used to view all Shell commands. You can use this command to find the usage of the Shell command. you only need to enter the help command after the command to be searched, and then you can see the content of the command to be queried.
　　
For example, view how to use the od command.
　　
$ Od -- help
　　
Whereis command
　　
The main function of this program is to find the location of a command. For example, the most common ls command is in the/bin directory. If you want to know which Directory a command exists, you can use the whereis command to query it.
　　
The command is generally in the following format:
　　
Whereis [option] command name
　　
Note: Generally, you can directly use the whereis command without any option, but you can also choose some of its options based on special needs.
　　
The meanings of the options in this command are as follows:
　　
B. search for binary files only.
　　
M. find the main file.
　　
S find the source
　　
U.
　　
For example, find the directory in which the ls command is located.
　　
$ Whereis ls
　　
Ls:/bin/ls/usr/man/man1/ls.1