The Linux command line is a text interface to your computer. Often referred to as the shell, terminal, console, prompt or various other names.
vim editor
There are 3 common modes of vim:
Normal mode
Insert mode
Command line mode
Normal mode: cursor can be moved, copied and pasted, deleted, etc.
vim filename.xxx # If not, open after creation, and open directly after opening and enter normal mode
yy # copy the current line
5yy #copy the next 5 lines
p # paste
dd # delete the current line
5dd # delete the next 5 lines
:set nu # set line number
:set nonu # cancel line number
G # come to the end
gg # Back to the first line
u # undo the operation just now
shift + g # Move the cursor to the tenth line
:wq # save and exit
:q! # Force exit (do not save the changes just now)
:q # If you have not edited after opening, you can exit like this, otherwise you can only use wq and q!
When opening the file, it is in normal mode, press i to enter insert mode (editable).
To return to normal mode from insert mode, press the ESC key.
Press: from normal mode to command line mode.
When vim pastes the code, the format is disordered. How to do?
:set paste # enter paste mode
Then press i to paste it. It should be noted that you need to exit the paste mode after pasting.
:set nopaste # Exit paste mode
How to find it with vim?
Press / in the normal mode, and then input the character string you want to find.
For example, if you want to find eg in a file, just:
/eg
Commands such as boot and restart
shutdown -h now # Shut down immediately
shutdown -h 1 # Shut down after 1 minute
shutdown -r now # restart now
halt # Shut down directly
reboot # reboot the system
sync # Flash the data in the memory to the hard disk
User switching and logout
su user name # just switch the user, will not change the original user's working directory and other environment variable directories
su-vth # Switch to the vth user, and switch the working directory and other environment variable directories to vth.
#Previous, the working directory is switched to /home/vth
sudo su # Authorize root privileges to the current user without switching the working directory. Only need to enter the current user's password.
# But this method requires the root user in the /etc/sudoers file
# root ALL=(ALL) ALL Copy a line and replace root with the username. This file is read-only,
# If you want to modify, you can raise the right.
su-xm # Switch to user Xiaoming
logout # Logout user in run level 3
exit # Exit the current user
su, sudo, su-xxx comparison:
If you have su, you have root privileges, without changing the directory and environment variables, and you must enter the password when switching.
su-xxx # For low-level to high-level, you need to enter a password, change the directory and environment variables.
sudo su # You only need to enter the current user's password when executing. But make sure to add the current stuff in /etc/sudoers
User Management
Linux users must belong to at least one group. If the group is not specified when adding the user, then it is a group by itself.
useradd xm # add user xm
useradd -d /home/dog xm # Add user xm and set the home directory to /home/dog
useradd -g xmzu xm # Create xm user and add it to the xmzu user group
# Note that the statement above must first exist in the xmzu group, otherwise it cannot work.
usermod -g shaolin xm # Change the group to which user xm belongs to shaolin
# Note that the above statement must exist in the shaolin group first, otherwise it will not work.
passwd xm # root user changes the password to xm
Note that the prompt is $ for ordinary users, # for root users
userdel xm # Delete the xm user, but keep the home directory it created
userdel -r xm # Delete the xm user and the home directory it created # Destroy the roots
id xm # View user information
When switching users with su-root, exit can return to the original user.
There is no need to enter a password when changing from a user with high authority to a user with low authority, and vice versa.
groupadd wudang # Create wudang group
groupdel wudang # Delete the wudang group. Note that you cannot delete the wudang group when there are members
