Directory permissions
Permissions For security reasons, all Unix systems including Linux have file permissions which allow you to control access to directories - who can read, write, or execute a file or command in a directory. In the extreme left is either a d or hyphen (-) indicating whether this is a directory or a file (occasionally you will also see an l indicating a link). Then you see three groups of the same three letters in the same order: r for read, w for write, x for execute, and the hyphen (-) for no permission given in that type. The first group of three letters is for the owner, the second group for the group, and the third the world. Whoever creates the file is the owner, and if more than one person is working on a project or needs access to this file they are given permission as a group, and finally how the file is open to anyone who has access to the system (the world). chmod, chown, chgrp The command to change file permissions is chmod (change mode). There are two ways for do...