For more general information on security, see Chapter 18 “Making Your System Secure” in Part II.
Three groups of users can access files: owner, group, and
other. File access is divided into three functions: read
permission, write permission, and execute permission.
Who Has Access? The three basic classes of users are:
Owner—Usually the person who created the file.
Group—Several users that have been grouped together by the system administrator. For example, the members of a department might belong to the same group.
Other—All other users on the system.
What Kind of Access? The access permissions on a file specify how that file can be accessed by the owner, group, and other.
Read Permission—Allows access to retrieve or view the contents of the file or directory.
Write Permission—Allows access to change the contents of the file or directory.
Execute Permission—For a file, allows access to run
the file (for executable files and scripts). For a directory, allows you to view the contents of files within the directory, and to run
commands, scripts, and actions within that directory.
With File Manager, you can view and change the access permissions for any
file or directory. See “Changing the Owner of a File or Directory” and “Changing Access Permissions” later in this chapter.
Examples. To make a directory private:
Change the directory's properties, giving yourself (the "owner") read, write, and execute permission, but give no permissions for "group" and "other." Then only you and the superuser can view the directory contents.
To make an action that you have created available for everyone to use, but protected so it is not inadvertently overwritten:
Change the file's properties, giving read and execute permission to "owner," "group," and "other." Don't give anyone write permission.
Default Permissions. The default permissions used when you create a new file or directory may be
altered by your system administrator. To determine your current
defaults, create a new file or directory, then choose "File" in the
File Manager menu bar, then choose "Properties". To change your default permissions, ask your system administrator.
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