What is the linux etc directory used for?

In Linux, the etc directory is the configuration file directory, which is used to store all configuration files and subdirectories required for system management; basically hardware and software configuration files are in this directory, such as "/etc /passwd" is the system user configuration file, "/etc/group" is the user group configuration file, and "/etc/xinetd.conf" is the configuration file of the xinetd service; by editing these configuration files, you can change and manage the system .

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

/etc

/etc directory is used to store configuration files in the system (stores all configuration files and subdirectories required for system management), basically all configuration files can be found here.

For example, /etc/passwd is the system user configuration file, /etc/group is the user group configuration file, /etc/xinetd.conf is the configuration file of the xinetd service, and /etc/resolv.conf is used to specify The DNS server address of this machine, etc.

By editing these files, you can change and manage the system.

etc is not an abbreviation, it means and so on, which comes from the French et cetera. When translated into Chinese, it means wait.

As for why the configuration files are stored under /etc, According to the original UNIX, what is placed here is a bunch of bits and pieces, called etc. This is actually a historical legacy.

• One way of saying it is et cetera. This is an older saying, that is, no matter what data or files, as long as they do not belong to other directories, they should be placed in the /etc directory.

• Another way of saying it, "Editable Text Configuration": Many people also regard the /etc directory as a place to place the configuration files of our system programs. So you often see directory introductions like this
  /etc - Usually contain the configuration files for all the programs that run on your Linux/Unix system.
  

The /etc directory is generally used to store the configuration files of the entire file system required by the program.

• /etc directory
  Contains many files. Many network configuration files are also in /etc.

• ##/etc/rc or/etc/rc.d or/etc/rc*.d

  Directory of scripts or scripts that are run when starting or changing run levels.
  

• /etc/passwd

  User database, the fields in which give the user name, real name, home directory, encrypted password and other user information.
  

• /etc/fdprm

  Floppy disk parameter table. Describes different floppy disk formats. Set with setfdprm.
  

• /etc/fstab

  Mount at startup The file system list automatically mounted by the -a command (in /etc/rc or equivalent startup file). Under Linux, it also includes information about the swap area enabled by swapon -a.
  

• /etc/group

  Similar to /etc/passwd, but it describes the group instead of the user.
  

• /etc/inittab

  The init configuration file.
  

• /etc/issue

  The output information of getty before the login prompt. Usually includes a short description or welcome message of the system. The content is determined by the system administrator.
  

• /etc/magic

  The configuration file of file. Contains instructions for different file formats, and file guesses the file type based on it.
  

• /etc/motd

  　Message Of TheDay, automatically output after successful login. The content is determined by the system administrator. It is often used to notify information, such as warnings about planned shutdown time.
  

• /etc/mtab

  The list of currently installed file systems. Initialized by scripts and automatically updated by the mount command. Used when a list of currently installed file systems is needed, such as the df command.
  

• /etc/ shadow

  The shadow password file on a system with shadow password software installed. The shadow password file moves the encrypted passwords in the /etc/passwd file to /etc/shadow, which is only readable by root. This makes deciphering The password is more difficult.
  

• /etc/login.defs

  Configuration file for the login command.
  

• /etc/printcap

  Similar to /etc/termcap, but for printers. The syntax is different.
  

• /etc/profile, /etc/csh.login,/etc/csh.cshrc

  When logging in or starting up File executed by Bourne or Cshells. This allows system administrators to establish a global default environment for all users.
  

• /etc/securetty

  Confirm the secure terminal, that is, which terminal allows root login . Generally only virtual consoles are listed so that it is impossible (or at least difficult) to break into the system via a modem or network and gain superuser privileges.
  

• /etc/shells

  List trusted shells.chsh command allows users to change the login shell within the scope specified in this file. The service process ftpd that provides FTP service on a machine checks whether the user shell is listed in the /etc/shells file. If not, it will not be allowed. User login.
  

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