The third lesson of Linux Learning--linux directory

• Unix- like system directory Structure

the directory structure of the Linux system is a hierarchical tree structure, which are mounted under the root filesystem "/", and the directory structure of the Linux system is listed below.

Detailed description of common directories in the Linux system directory structure

Directory	Describe
/home	The directory contains the home directory for each user on the Linux system, and the subdirectory name is named after the user name
/root	The directory is the root user's home directory
/bin	This directory contains commonly used command files and cannot contain subdirectories
/sbin	This directory contains the command files used by the system administrator and root user
/dev	This directory contains most of the device files, such as disks, optical drives, etc.
/lib	The directory and subdirectories of this directory contain shared files and kernel module files for Linux Systems
/lib64	The directory and its subdirectories contain shared files and kernel module files for the version Linux system
/tmp	This directory contains some temporary files
/mnt	This directory provides a default mount directory for some devices ( hard disk ) mounts
/boot	The directory contains kernel files and boot loader ( such as GRUB) files for Linux Systems
/opt	This directory contains installation files for some third-party applications
/media	This directory provides a default mount directory for devices such as discs, floppy disks, andU disks.
/var	This directory stores infrequently changing data, such as system logs, print queues,DNS database files, etc.
/misc	This directory is used to indicate the public mount point of the NFS Directory
/etc	This directory contains Most of the configuration files on the Linux system and it is recommended that you back up the configuration files before modifying them
/usr	This directory contains programs and data that can be used by all users
/net	This directory is used to support the mounting of shared directories on other operating systems over the network, such as NFS Shared Directories
/srv	This directory contains the data directory to be used after some services have been started.
/sys	While the Linux system provides hot-swappable capabilities, the directory contains the detected hardware settings, which are converted to device files in the / dev Directory
/proc	The directory is a virtual file system, it does not exist on disk, but has the kernel in memory, to provide information about the system
/selinux	The directory is the selinux configuration directory, andselinux ( security enhanced Linux) is a linux A mandatory access control implementation mechanism in the system can enhance The security of Linux system
/lost+found	The directory is empty in most cases. If there is a sudden power outage at work, or if you are not shutting down normally, some files will not be found when restarting the computer, and for these files, theLinux system places them in this directory .

• User Directory

located in /home/usr, called user working directory or home directory

Presentation mode:

/home/usr~

• Access rights

User can control the degree of access to a given file or directory, a file or directory may have read, write, and Execute permissions

• Read Permissions (r) for a file, have permission to read the contents of the file, and for the directory to have the Browse directory permission
• Write Permissions (W) for the file, has the new, modifies the file content the permission, to the directory, has the deletion, moves the file inside the directory the permission
• Executable Permissions (x) for a file, have permission to execute the file, and the user has permission to enter the directory for the directory

Note: usually The Unix/linux system allows only the owner or Superuser of the file to change the file's read and Write permissions

Example Description:

The first letter represents the type of file : "D" represents a folder,"-" represents a normal file,"C" represents a hardware character device,"B" represents a hardware device,"s" Represents a pipeline file, and"L" represents a soft connection file. The following 9 letters represent three groups of permissions: The file owner, the user group, and other users.

Each user has its own read, write, and Execute permissions:

• the first set of permissions Controls access to their own file permissions, and Owner permissions
• The second set of permissions controls the permissions of the user to access the files of one of the users who are in the same group
• The third set of permissions controls the permissions of other users to access a user's files

These three sets of permissions give the user different types ( i.e. owner, user group and other users ) ability to read, write and execute

• Operation of the Directory

Additions and copies of catalogs

Directory New command:mkdir

Create one or more new empty directories

Common Options Parameters "-P" for recursive creation of multi -level catalogs

copy of directory command:CP

Copy the source directory to the target directory, supporting the simultaneous renaming of the copy

common option Parameter "-a" for all copies

common option parameter "-F" for Force copying

Deletion of directories

Empty Directory Delete command:rmdir

Delete one or more empty directories

common option Parameter "-P" for recursive deletion of multi-layered empty directories

non-empty directory Delete command:RM-RF

Recursive deletion of non-empty directories

common option Parameter "-r" for recursive deletion

common option parameter "-F" for Force removal

Moving and renaming of directories

Directory Move renaming command:MV

Moving the directory Renaming of directories Renaming of directory moves at the same time

For example:

MV a b # change A to BMV C b/A # move C to the B directory MV D b/C # move D to B Change to C in the directory

The third lesson of Linux Learning--linux directory