Root file system: Contains the main programs and data that make the Linux system run. When the kernel starts, it will search for the root file system on the storage device, and the root file system will be mounted on "/".
The location of the root file system:
****** The root file system is stored in the Flash memory.
******Flash memory is divided into multiple partitions, the first partition, the second partition, the third partition, etc.
******First partition: used to store Linux kernel image files (stored in a separate partition).
******Second partition: used to store the root file system
******Third partition: store other common file systems, (the operation of the operating system does not depend on the third partition)
The directory structure description of Linux root file system:
******The root file system follows the FHS standard (Filesystem Hierarchy Standard)
******bin directory: Store the basic commands that users can use.
******sbin directory: stores the commands used by the system administrator.
******boot directory: store static files used by the boot loader
******root directory: root user's directory
******home directory: user directory For every ordinary user, there is a subdirectory with the same name as the user name under the /home directory, in which user-related configuration files and private files are stored.
******etc directory: stores various system configuration files
******dev directory: store device files and some special files
******opt directory: store additional software in this directory
******mnt directory: the mount directory of the temporary file system, used to mount the file system that needs to be used temporarily
******lib directory: store shared library files and some driver modules
******proc directory: is an empty directory, as the mount directory of the proc file system, the proc file system is a virtual file system, it exists in the memory, the directories and files in the proc file system are the kernel Temporarily generated.
******tmp directory: is an empty directory used to store temporary files. Some programs that need to store temporary files use /tmp
******usr directory: store shared, read-only files and programs. The files in this directory can be shared by multiple users.
******var directory: store variable files, such as log files, log files, and temporary files.