
In a multi-user environment, security of user and system data is important. Linux has three specific, or distinct, classes:
r - read permission which grants the ability to read a file.
w - write permission which grants the ability to modify a file.
x - execute permission which grants the ability to execute a file.
The list above shows the symbolic notation of each permission in bold text. Each permission also has an octal notation:
r - 4
w - 2
x - 1
To view permissions, type
ls -l ~/
which will output a list of the directories and files in the current user's home directory. For example:
drwxr-xr-x 2 username usergroup 4096 2009-12-17 11:10 Documents
The first column, which contains drwxr-xr-x, can be interpreted as follows:
File Type | User Permissions | Group Permissions | Others Permissions |
---|---|---|---|
d - directory | rwx - read, write, and execute permissions for the user. | r-x - read and execute permissions for the group. | r-x - read and execute permissions for all others. |