4-2-1 in UNIX / Linux world
In UNIX / Linux world, 4 represents readable (R), 2 represents written (W), 1 represents executable (x)
If you have 7 = 4 2 1 permissions, you can fully control the files on behalf of this person.
Take 0777 as an example:
Remove 0, the first 7 represents the owner, the second 7 represents group users, the third 7 represents other users
0777 The three privileges that represent all people have "readable / write / execute", that is, fully controlled files.
Take 0775 as an example:
That is, the owner and group users can fully control the file, while other users only have readable / writable permissions 4 1 = 5
Take 0755 as an example:
That is, the owner fully controls the file, and the group users and other users only have read / write-on-permissions 4 1 = 5
If it is under the Linux operating system, you can change the file file_name by entering the command: chmod 777 file_name to get readable, writable, executable permissions.
