Directory structure and content under Linux

With so long a Linux system, sometimes which file should be in the unknown, so for the directory structure under the root note:

/bin bin is the abbreviation for binary. This directory holds the most frequently used commands.
/ boot Here are some of the core files used when starting Linux, including some connection files and image files.
/dev Dev is an abbreviation for device. This directory is a Linux external device that accesses the device in Linux in the same way that it accesses the file.
/etc This directory is used to store all the configuration files and subdirectories required for system administration.
home directory, in Linux, each user has its own directory, which is typically named after the user's account name.
/lib This directory contains the system's most basic dynamic connection shared library, which acts like a DLL file in Windows. These shared libraries are required for almost all applications.
/lost+found This directory is generally empty, and when the system shuts down illegally, some files are stored here.
/media Linux System will automatically identify some devices, such as USB flash drive, optical drive, etc., when identified, Linux will attach the identified device to this directory.
/MNT System provides this directory for users to temporarily mount other file systems, we can mount the CD-ROM drive on the/mnt/, and then enter the directory to view the contents of the CD-ROM.
/opt This is the directory where additional installation software for the host is placed. For example, if you install an Oracle database, you can put it in this directory. The default is empty.
/proc This directory is a virtual directory, it is the mapping of system memory, we can access this directory directly to obtain system information. The contents of this directory are not on the hard disk but in memory, we can also directly modify some of the files inside, such as can be used to block the host ping command, so that others cannot ping your machine:
echo 1 >/proc/sys/net/ipv4/icmp_echo_ignore_all
/root The directory is a user home directory for system administrators, also known as super-privileged users.
/sbin S is the meaning of super user, which is a system manager used by the system administrator.
/selinux This directory is a unique directory of Redhat/centos, SELinux is a security mechanism, similar to Windows Firewall, but this mechanism is more complex, this directory is to store selinux related files.
/srv This directory holds data that needs to be extracted after some services are started.
/sys This is a big change in the linux2.6 kernel. In this directory, a new file system Sysfs is installed in the 2.6 kernel, and the Sysfs file system integrates the information of the following 3 file systems: Proc File system for process information, DEVFS file system for devices, and devpts file system for pseudo terminal. The file system is a visual reflection of the kernel device tree. When a kernel object is created, the corresponding files and directories are also created in the kernel object subsystem.
/ tmp This directory is used to store some temporary files.
/ usr This is a very important directory, the user's many applications and files are placed in this directory, similar to the Program Files directory under Windows.
/usr/bin The application that the system user uses.
/usr/sbin more advanced hypervisor and system daemon used by super users.
/USR/SRC The default placement directory for the kernel source code.
/ var This directory is stocked with things that are constantly expanding, and we are accustomed to placing directories that are often modified in this directory. Includes various log files.

In the Linux system, there are several directories are more important, usually need to be careful not to accidentally delete or arbitrarily change the internal files. /etc: Also mentioned above, this is the configuration file in the system, if you change a file in this directory may cause the system will not start. /bin,/sbin,/usr/bin,/usr/sbin: This is the placement directory of the system preset execution files, such as LS is in the/bin/directory. It is worth noting that,/bin,/usr/bin is the instruction that is used to the system user (except for the generic account rooted in root), and/sbin,/usr/sbin is the instruction to use for root. /var: this is a very important directory, the system ran a lot of programs, then each program will have a corresponding log generated, and these logs are recorded in this directory, specifically in the/var/log directory, the other mail preset placement is also here.

Directory structure and content under Linux