Notes for first-time CentOS learning

1. linux is case sensitive. all content in Linux is saved as files, including/dev/sd [a-p] when the hardware hard disk file is/dev/sr0. linux does not rely on extensions to differentiate file types, but we often add extensions to differentiate files. Example: compressed package: .gz.bz2 & n

1. Linux is case sensitive

2. all content in Linux is saved as files, including hardware

Hard disk file/dev/sd [a-p]

CD files/dev/sr0

3. Linux does not rely on extensions to differentiate file types, but we often add extensions to differentiate files.

For example: compressed package:. gz. bz2 .tar.bz2. tgz

Binary package:. rpm

Webpage files:. html. php, etc.

Script File:. sh

Configuration File:. conf

 

4. all storage devices in Linux can be used only after being mounted, including hard disks, USB disks, and optical disks.

 

5. Windows programs cannot be installed and run directly in Linux

 

6. Functions of Linux directories

Directory name	Directory function
/Bin/	The Directory for storing system commands, which can be executed by both common users and super users. however, commands placed in/bin can also be executed in single-user mode.
/Sbin/	Saves commands related to system environment settings. only super users can use these commands to set the system environment. However, some commands can be viewed by common users.
/User/bin/	The directory where system commands are stored. common users and super users can execute these commands. these commands are irrelevant to system startup and cannot be executed in single-user mode.
/User/sbin/	Unnecessary system management commands for storing the root file system, which can only be used by Super users
/Boot/	The system startup Directory stores system startup files, such as kernel files and grub files.
/Dev/	Device file storage location
/Etc/	The location where the configuration file is saved. Such as user accounts and passwords, service startup scripts, and common service configuration files.
/Home/	Home directory of common users. Each user has a default logon location, which is the home directory of the user, the home directory of all common users is to create a directory with the same user name under/home. For example, the home directory of user1 is/home/user1.
/Lib/	Location where the system calls the function library
/Lost + found/	When the system crashes or the machine shuts down unexpectedly, some file fragments are generated here.
/Media/	Mount Directory
/Opt/	Third-party software storage location
/Proc/	In a virtual file system, the data in this directory is not saved to the hard disk, but to the memory. It stores the system kernel, processes, external device status, and network status.
/Sys/	Virtual File System. It stores kernel-related information.
/Root/	The home directory of the Super User.
/Srv/	Service Data Directory. After some system services are started, you can save the required data in this directory.
/Tmp/	Temporary directory. The directory where the system stores temporary files. all users in this directory can access and write files.
/Usr/	System software Resource Directory. Note that usr is not a user.
/Var/	Dynamic data storage location. Stores cached files, logs, and files generated by software.

 

7. server considerations

The remote server cannot be shut down, but can only be restarted. Service should be disabled upon restart

8. specify reasonable password specifications and update them regularly

9. reasonably assign permissions

10. regularly back up important data and logs