The first day of Linux learning, a common command

Linux System Fundamentals:
1, composed of a single small program of freedom, the combination of small procedures to complete the task of responsibility.
2, all documents,
3, try to avoid capturing the user interface, that is, the user input commands can be directly returned results.
4. The configuration file is saved in plain text format.
GUI Interface: graphical interface
CLI Interface: Command interface, requires user input command.
Command prompt: Prompt
Root Admin #
Normal User $
Related commands for user actions (including, adding, modifying, deleting a user's commands)
New, delete user's command:
Useradd User Name
The system administrator command creates a new user.
Options:
-D: Create a new user, use the default root directory as the root of the new user,
-M: If the directory does not exist, use-M to create a new directory as the root of the new user.
-S: Specifies the shell to which the user is logged on.
-B: If you do not use the-D home_dir default path, the default base directory is used. Base_dir plus the account name is the home directory. If the-M option is not used, the base_dir must already exist.
-c A description of the login.
-E: User will be disabled date, date format: YYYY-MM-DD

Userdel [option] User name delete system user name
Options:
-R Deletes the user and deletes all directories for that user at the same time.
-F Force Delete user, if the user is logged in state, after deletion, the connection to Shh will not be disconnected. The user can no longer log on after exiting.
To modify a user name:
usermod [Options]
Ways to switch users:
SU: Full name switch User
Su [-l] User name
SU User name
To modify a user password:
passwd: Password (password to meet complex rules)

Common commands:
Ls:list list all files in the specified directory
Option:-L (Long) displays file details
PWD: Displays the current path. /Representation system root directory

The first day of Linux learning, a common command