Linux permissions Explained

From left to right, the first digit represents the permissions of the file owner, the second digit represents the permissions of the same group of users, and the third digit represents the permissions of the other user.

And the specific permissions are represented by a number, the Read permission equals 4, with R, the permission to write is equal to 2, with W, the execution of the permission equals 1, denoted by x;

Through the combination of 4, 2, 1, the following permissions are obtained: 0 (no permission); 4 (Read permission); 5 (4+1 | Read + execute); 6 (4+2 | Read + write); 7 (4+2+1 | Read + Write + execute)

Take 755 as an example:

The first bit 7 equals 4+2+1,rwx, the owner has read, write, execute permission;

The second bit 5 equals 4+1+0,r-x, the same group of users have read, execute permissions but no write permission;

Third bit 5, ditto, is also r-x, other users have read, execute permissions but do not have write permission.

Common Linux file permissions are listed below:

444 r--r--r--
RW-------
644 rw-r--r--
666 rw-rw-rw-
RWX------
744 rwxr--r--
755 Rwxr-xr-x
777 Rwxrwxrwx

Linux permissions Explained