Chmod method of using numbers to represent permissions

Prerequisites:

Mode permission set string, format: [Ugoa ...] [[+-=][RWXX] ...] [,...]

where u represents the owner (user), g means that the owner belongs to the same group (group), O denotes other persons (other), and a shows all three;

+ means to increase the permissions,-the cancellation permission, = The unique set of permissions;

R: Indicates readable, w indicates writable, and X indicates executable.

syntax: chmod ABC file

Where A,b,c is a number, a means that user,b represents Group,c's permission to represent other.

R=4,w=2,x=1

To rwx (readable, writable, executable) properties, 4+2+1=7

To rw-(readable, writable, non-executable) properties, 4+2=6

To R-w (readable, non-writable, executable) properties, 4+1=5

Example:

chmod a=rwx file and chmod 777 file effect are the same

chmod ug=rwx,o=x file and chmod 771 file effect are the same

Use chmod 4755 filename to give the program root privileges

Chmod method of using numbers to represent permissions