The access mode, sometimes known as file permission or access permission, is a system, defined by the programmer, that defines the level of access to objects, such as individual files and directories, for different types of users. There are three types of basic access a user can be given: read permission, write permission, and execute permission. These types of access are incorporated so as to enforce integrity, confidentiality, or availability constraints. The different types of access mode have different meaning depending upon whether they are applied to a directory or a regular file.

The read permission for a regular file allows the user to copy and view the file. The write permission for the same file allows the user to edit, delete, and overwrite that file. The execute permission allows a user to run a program or shell script when applied to a file.

These different...