information on using LL or ls-l to view files under Linux(ll and ls-l differences: LL will show hidden files in the current directory, and Ls-l will not)file information is divided into: file type, permissions, number of links, the user, the user group, file size, last modified time, file name, concrete can see.
I. File type:d: Folder-: Normal fileL: Links (Windows-like shortcuts)B: block device files (e.g. hard drives, optical drives, etc.)P: Pipeline fileC: Character device files (e.g. serial devices such as cats)s: Set of interface files/data interface files (e.g. a Mysql.sock file is generated when starting a MySQL server)
ii.. File Permissions
| Permissions |
corresponding numbers |
Significance |
| R |
4 |
Readable |
| W |
2 |
can be written |
| X |
1 |
Executable |
-: Display when a location is empty--indicates that this permission is not availableThe permission bits consist of 9 bits, the first 3 bits represent the permissions of the file owner, the Middle 3 bits represent the permissions of the user group to which the file belongs, and the last 3 bits represent the permissions of the other user. examples are as follows:
Drwxr-xr-x 2 root mail 4096 January 03:44 accountindicates that the folder Account,root is his owner, has a readable writable executable permission; Mail is his own user group with readable, executable permissions, no writable permissions, other users have readable, executable permissions for this folder, and no writable permissions Change Permissions command:chmod permission file nameThere are two uses of chmod1.chmod user + (-) permission file name
| User |
Significance |
| U |
Owner (user) |
| G |
Owning Group (group) |
| O |
Others (Other) |
| A |
All of them (all) |
(Increase permissions with +, reduce permissions with-, directly equal to the permissions with =) Example: Adding readable permissions to other users of the file Test.txtchmod o+r test.txt
Permissions Additional instructions:The file has default permissions:
| Type |
Default Permissions |
| File |
rw-rw-rw- |
| Directory |
Rwxrwxrwx |
but this permission is not necessarily the default permission for our Linux system, each system has a permission mask (unmask)Viewing the permission mask with a command (Umask viewing a number mask; umask-s viewing a character mask)Number Mask: Default mask minus the permission represented by the number maskcharacter Mask: The intersection of default flooding and character masks represents permissionscommand to modify the permission mask: umask 007 (or umask u=rw,g=rwx,o=r) 2.chmod Permissions numeric file nameThe permission number consists of 3 digits, the 1th digit represents the owner's permission, the 2nd digit represents the permission of the owning group, and the 3rd digit represents the other person's rights .Example: The Test.txt file change permission for the file owner can read the writable executable, the file belongs to the group can be read and writable executable; Other people can read executable is not writable. chmod 775 Test.txtDescription: Number is the value of the corresponding permission and. For example 7=4+2+1, so 7 represents a readable writable executable. 5=4+1, so 5 represents a readable executable that is not writable. 0 means unreadable, non-writable, non-executable
Iii. The owner of the document and the group to which it belongs1. Change the file ownercommand: Chown user name fileExample: Chown work test.txt (change the owner of the Test.txt to work) 2. Change the group to which the file belongscommand: CHGRP group name fileExample: Chgrp named Test (change the group of Test to named)
Other:1.chmod and Chgrp, chown have a parameter-R, you can recursively change the directory and its sub-directories with the permissions, etc.2. Some ll will find a "." After the first paragraph has been found. or "+" as shown in:looked it up on the internet,"." Represents a security label with SELinux, with security context properties (can be viewed with Ll-lz)"+" means that the file has security measures applied to other access controls(interested people can check their own, I did not go to query too much content.) )
File types and permissions for Linux
