Question

What are the user access control permissions for file and directory defined in Unix/Linux? Draw a table showing permission type and symbol.

Hint:

Unix/Linux uses Read, Write, and Execute permissions for User, Group, and Others to control file and directory access.

Answer 1

Unix/Linux systems control access to files and directories using a permission model based on three types of permissions applied to three categories of users:

• Permission Types:
  • Read (r): Allows viewing the contents of a file or listing the contents of a directory.
  • Write (w): Allows modifying the contents of a file or adding/removing files within a directory.
  • Execute (x): For files, allows execution as a program; for directories, allows access to enter or traverse the directory.
• User Categories:
  • User (u): The owner of the file/directory.
  • Group (g): Other users belonging to the file’s group.
  • Others (o): All other users.

\begin{tabular}{|c|c|l|} \hline Permission & Symbol & Description
\hline Read & r & Permission to read file contents or list directory
Write & w & Permission to modify file contents or directory contents
Execute & x & Permission to execute a file or access a directory
No Permission & - & Absence of the respective permission
\hline \end{tabular} These permissions combine to form access rights for each user category, often displayed as a 9-character string (e.g., rwxr-xr--).