Every file or directory on a server has a set of access permissions associated with it. These include the owner of a file, the group a file is associated with, and who has read, write, and execute permission on that file. These permissions allow you to choose who can use your files, and control what they can do with them. There are three groups in terms of file access, and three different permission types they can receive.
Owner: the Owner group consists only of the owner of the directory.
Group: The Group permissions apply only to the group that has been assigned to the file or directory, they will not effect the actions of other users.
Everyone: the Other group consists of all other users eg. website visitors.
Each file or directory has three basic permission types:
Read: this allows a user or program the ability to read the data in a file
Write: the Write permission allows a user or program the ability to write new data into a file, and to remove data from it
Execute: the Execute permission allows a user or program the ability to execute a file, if it is a program or a script
Permission – Numeric Value
0 – No Permission
1 – Execute
2 – Write
3 – Write + Execute
4 – Read
5 – Read + Execute
6 – Read + Write
7 – Read + Write + Execute