/proc
The Linux kernel provides a mechanism for accessing data structures inside the kernel at runtime through the /proc file system and changing kernel settings.
The proc file system is a pseudo file system that only exists in memory and does not occupy external memory space.
It provides an interface for accessing system kernel data in the manner of a file system.
/sys
sysfs is a ram-based file system, like proc
Sysfs file system is a special file system similar to proc file system, used to organize devices in the system into a hierarchical structure and provide user-mode programs with detailed kernels Data structure information.
In fact, in the user mode, you can view some drivers or devices in the kernel mode by accessing the sys file system.
/bin
The commands required by the base system are located in this directory and are the commands required by the minimal system.
/tmp
temporary file directory, sometimes when the user runs the program, temporary files will be generated. /tmp is used to store temporary files.
/usr
This is the directory where the system stores programs, such as command help files.
Similar to the /lib directory, /usr/lib is the storage directory of library files.
/usr/local This directory is generally used to store the storage directory of user-compiled and installed software; it is generally software installed through source code. If the installation directory is not specified If so, it is usually installed in this directory.
The content of the /var
directory changes frequently. You can tell by the name. We can understand it as the abbreviation of vary. There is /var/log under /var, which is the directory used to store system logs.