1. Command name: Man
Execution permission: All Users
Function Description: Get help information
Syntax: Man [command or configuration file]
View the help information of the LS command. After the help information is displayed, Press space to next page, press Enter next line, and press Q to exit [root @ localhost ~] # Man ls: view the help information of the configuration file services. After the help information is displayed, press the space on the next page, press Enter next line, and press Q to exit [root @ localhost ~] # Man services
If the command and configuration file have the same name, man displays the help information of the command by default. You can use man 5 to specify the help information of the configuration file, for example, MAN 5 passwd.
2. Command name: info
Execution permission: All Users
Function Description: Get help information
Syntax: info [any keyword]
[Root @ localhost ~] # Info ls
3. Whatis, apropos, and -- Help
Execution permission: All Users
Function Description: Get Brief description of the index.
Syntax: whatis [any keyword], apropos [any keyword], command -- Help
[Root @ localhost ~] # Apropos fstabendfsent [getfsent] (3)-handle fstab entriesfstab (5)-static information about the filesystemsfstab-Decode (8)-run a command with fstab-encoded encode (3) -Handle fstab entriesgetfsfile [getfsent] (3)-handle fstab entriesgetfsspec [getfsent] (3)-handle fstab entriesnfs (5) -fstab format and options for the NFS file systemssetfsent [getfsent] (3)-handle fstab Entries [root @ localhost ~] # Whatis lsls (1)-List Directory contentsls (1 p)-list directory contents [root @ localhost ~] # [Root @ localhost ~] # Ls -- Help
4. Command name: Help
Execution permission: All Users
Function Description: view the help of shell built-in commands.
Syntax: Help Command
[Root @ localhost ~] # Help CD