File and Folder Permissions

File ownership is an important component of UNIX that provides a secure method for storing files. Every file in UNIX has the following attributes:

• Owner permissions: The owner’s permissions determine what actions the owner of the file can perform on the file.
• Group permissions: The group’s permissions determine what actions a user, who is a member of the group that a file belongs to, can perform on the file.
• Other (world) permissions: The permissions for others indicate what action all other users can perform on the file.

Here’s a full table of possible numbers and which permissions they are representing:
1 –x execute
2 -w- write
3 -wx write and execute
4 r– read
5 r-x read and execute
6 rw- read and write
7 rwx read, write and execute

example:

777 world writeable (rwx)
775 Owner (rwx), group(rwx), other (rx)
755 Owner (rwx), group and other (rx)