is a system management program used by system administrators.
/selinux：
This directory is unique to Redhat/CentOS. Selinux is a security mechanism, similar to the Windows firewall.
But this mechanism is more complicated, this directory is to store selinux-related files.
/srv：
This directory stores some data that needs to be extracted after the service is started.
/sys：
This is a big change in the Linux2.6 kernel. A new file system sysfs in the 2.6 kernel is installed in this directory.
The sysfs file system integrates the information of the following three file systems: proc file system for process information, devfs file system for devices
filesystem and the devpts filesystem for pseudo-terminals.
The file system is a visual reflection of the kernel device tree.
When a kernel object is created, corresponding files and directories are also created in the kernel object subsystem.
/tmp：
tmp is an abbreviation of temporary (temporary). This directory is used to store some temporary files.
/usr：
usr is the abbreviation of unix shared resources (shared resources), this is a very important directory, many applications of users
and files are placed in this directory, similar to the program files directory under windows.
/usr/bin：
Applications used by system users.
/usr/sbin：
More advanced hypervisors and system daemons used by superusers.
/usr/src：
The directory where the kernel source code is placed by default.
/was:
View the location of the current command pwd
switch path
cd … go back to the previous level
cd / back to the root directory
cd ~ returns to the user directory
If you are a root user, cd ~ is equivalent to cd /root
If it is a normal user, cd ~ is equivalent to cd /home/current user name
cd folder switch directory
View the files in the directory
ls displays the names of folders or files under the current folder without line breaks
ll Newline displays the names of folders or files under the current folder, as well as detailed information about these folders or files
ls -al -a is to display hidden files -l is to display in a more detailed list (list all)
ll -h wrap the file and display its size (with units)
install lrzsz
02. Daily operation order
ping View network status
ifconfig view network configuration
ip addr view network configuration
clear clears the console
03. User operation command
su switch users (root needs to enter a password)
exit log out
04. Directory operation
dir View the folders in the current directory
mkdir creates a folder
rmdir delete folder
05. File operation
touch to create a file
cat view file content
var is the abbreviation of variable (variable). This directory stores things that are constantly expanding. We are used to storing those objects that are often modified
recorded in this directory. Includes various log files.
/run：
It is a temporary file system that stores information since the system was started. When the system restarts, the files in this directory should be deleted or cleared. if
You have the /var/run directory on your system, which should point to run.
Two, common commands
1. Switch path
cd ... go back to the previous level
cd / back to the root directory
cd ~ returns to the user directory
If you are a root user, cd ~ is equivalent to cd /root
If it is a normal user, cd ~ is equivalent to cd /home/current user name
cd folder switch directory
2. View the files in the directory
ls displays the names of folders or files under the current folder without line breaks
ll Newline displays the names of folders or files under the current folder, as well as detailed information about these folders or files
ls -al -a is to display hidden files -l is to display in a more detailed list (list all)
ll -h wraps the file and displays its size (with units)
3. Daily operation commands
ping view network status
ifconfig view network configuration
ip addr view network configuration
clear clears the console
4. Directory operation
dir View the folders in the current directory
mkdir create folder
rmdir delete folder
5. File operation
touch to create a file
、
echo content > file : add content in the file
cat view file content
Var is the abbreviation of variable (variable). This directory stores things that are constantly expanding. We are used to putting those frequently modified directories in this directory. Includes various log files.
If you continue to perform the above operation, the original content will replaced :
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If there are two greater than signs , it is to continue editing the file in the file content
/run：
It is a temporary file system that stores information since the system was started. When the system restarts, the files in this directory should be deleted or cleared. If you have a /var/run directory on your system, it should point to run.
rm delete files: will ask you to confirm whether to delete
rm -f file : delete the file directly without asking you for confirmation
6. Complicated file operations
**mv move files, **you can modify the name at the same time
**cp copy files
rm -r file:**recursively delete
rm -rf file : delete directly (preferably not used)
**cp copy files
rm -r file:**recursively delete
rm -rf file : delete directly (preferably not used)