How Linux modifies permissions for a file or directory (chmod)

The chmod command is a command used on Linux to change permissions, and-R is a recursive traversal of subdirectories, because the file you are manipulating uses the * wildcard character. 777, the first 7 represents the permissions of the owner of the file, the second 7 represents the permissions of the group to which the file belongs, the third 7 represents the permissions of the other user, 7=4+2+1, and the permissions in Linux can be described by numbers. The following are the specific expressions:

4, the user ID is set at execution time, and is used to authorize the file owner-based process instead of the user who created the process.
2, when executed, sets the user group ID, which is used to authorize the process based on the group of files, rather than on the user who created the process.
1, set the sticky bit.

Second, the detailed use of the chmod command is as follows, there is no understanding can be viewed slowly.
chmod----Changing the access mode of one or more files (mode)

chmod [options] mode files

This feature can only be used by a file owner or a privileged user to change the file access mode. Mode can be expressed in digital form or in the form of who opcode permission. Who is optional and the default is a (all users). Only one opcode (opcode) can be selected. Multiple mode can be specified, separated by commas.


Grant a file to anyone full rights: Chmod-r 777  filename  

How Linux modifies permissions for a file or directory (chmod)