Linux File System Level and linux level

Linux File System Level and linux level

The purpose of this standard is to define the standard path of the Linux File System so that developers and users can find what they need in a reasonable place.

The general idea of Linux File layout is to divide files and directories into the following three groups:

Unique files and directories for a specific system running Linux, such as startup scripts and configuration files.

Read-Only files and directories that can be shared between different systems running Linux, such as executable applications.

Readable and writable directories that can be shared between different systems running Linux or other operating systems, such as the user's home directory.

The top-level structure defined by FHS contains some required subdirectories and a small number of optional directories.

/Bin: Contains binary files that can be used by root users and standard users. They can all run in single-user mode, that is, other directory structures can be run independently without being loaded. For example, the core commands such as cat and ls can be found here, and the command sh is also included.

/Boot: This directory contains the files needed to start the Linux system. These files are usually relatively small, and the file length cannot exceed 100 MB.

/Dev: This directory contains special device files mapped to hardware. For example,/dev/hda maps to the first IDE disk.

/Home: not required. Directory used to place user files. Under normal circumstances, each user will have a subdirectory with the same login name under this directory, and this subdirectory is their default login directory.

/Etc: the configuration file is placed in this directory. The most famous file in the/etc directory may be the passwd file, which contains the user information in the system. Other useful files include fstab, hosts, and httpd ).

/Lib: This directory contains the basic shared function libraries and kernel modules, especially the files required when the system is started or the system is in single-user mode.

/Media: this top-level directory is used to include other subdirectories that load removable media. The objective is to eliminate unnecessary top-level directories such as/cdrom and/floppy.

/Mnt: This directory is only used to facilitate the temporary loading of some other file systems.

/Opt: This directory is used by software vendors when they add software to the system. This directory is mainly available to third-party vendors.

/Root: not required. This directory contains files used by the root user.

/Sbin: This directory contains commands that can only be used by the system administrator, and commands that are required when the system is started or in single-user mode. The command fsck, halt, and swapon are in this directory.

/Srv: This directory contains site-specific Read-Only configuration files, which are not yet widely used.

/Tmp: temporary files placed in this directory. The system usually clears this directory at startup (but not always.

/Usr: This is a very complex level-2 file system. In this directory, it usually contains all the system-class commands and function libraries except the files required to enter the single-user mode at system startup. It contains many subdirectories, such as/bin,/lib,/X11R6, And/local.

/Var: The data stored in this directory will change frequently, such as the queue file used for printing, the application log file, and the mail queue directory.