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→File Permissions
Since the Unix / Linux operating file systems allow for '''multiple user accounts''' it is essential<br>to have a system to '''share''' or '''limit''' access to directories and files contained in those different user accountswithin the file system.
[[Image:listing-file-directory.png|thumb|right|400px|Detailed directory listing showing permissions for a '''directory'''<br>and a '''regular file'''.]]
Users that <u>own</u> those ''directories'' and ''regular files'' are referred to as '''users''', users that belong within the <u>same group</u> are referred to as '''same group members''', and those users are do <u>NOT</u> belong to a particular group are referred to as '''other group members'''.
'''NOTE:''' In this course, we cannot create groups or assign users to groups in the '''Matrix''' server.<br>Instead, you will learn how to those tasks when or if you take a Unix/Linux administration accountcourse.<br>On the other hand, you can change which '''user''', '''same group members''' or '''other group members'''<br>can access or NOT access a directory or regular file.<br><br>
[[Image:directory-permissions.png|thumb|right|350px|Permissions of a '''directory''' that contain subdirectories and regular files.]]
File Permissions consist of '''two-layers''':<br><br>'''First''', the permissions of a '''directory''' that contains regular files, and '''second''', permissions of the ''regular files'' within a directory.
Permissions for Directory files directories have a different meaning than permissions for '''regular files'''. Refer to the diagrams to the right to see the explanation of permissions and how they differ between a directory and a regular file.
A symbol ''dash'' "'''-'''" indicates that the permission has '''NOT''' been granted.
'''<span style="font-style:italic">Octal (Absolute) Method:</span>'''
[[Image:octal-permissions.png|thumb|right|150px|using Using octal numbers to represent setting file permissions.]]You can also use '''octal numbers''' to represent '''set''' permissions. This method is a short-cut and may require less typing than using the ''symbolic'' method. You can only use this method to '''set''' file permissions (as opposed to ''add'' or ''remove'' permissions.
Since 1 octal digit represents 3 binary digits, one octal digit can represent the <span style="font-family:courier;font-weight:bold;">rwx</span> permission granted or NOT granted. The permissions '''rwx''' are be in the form of 3 binary digits (1 represents the permission granted and 0 represents the permission NOT granted).
