Types of Permissions

In the Linux environment, the file system is shared among users. Permissions guard against unwanted access to a user's files and directories. Permissions are represented by bits that control who may read, write and execute the contents of files and directories.

Every file or directory has a set of permissions that determines who can do what with it.

Permission	Permission Symbol	Description of Permission
Read	r	Read permission on a file allows users to read or copy the contents of that file. Read permission on a directory allows a user to list the contents of the directory.
Write	w	Write permission on a file allows users to modify files. Write permission on a directory allows other files or directories to be added to or removed from that directory.
Execute	x	Execute permission on a file allows users to execute the file. Execute permission on a directory allows the user to list or search the contents of a directory. It is used with executable programs and script files.
No access	-	No access indicates no access to the file or directory.