operating-system/problem-40 at main · gowthamch54/operating-system · GitHub

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User Types
Owner (User): The user who owns the file.

Group: A set of users who share the same group.

Others: All other users who are not the owner or part of the group.

File Access Permissions
Permissions are typically represented using a combination of three attributes:

Read (r): Permission to read the contents of the file.

Write (w): Permission to modify the contents of the file.

Execute (x): Permission to execute the file (if it's a script or a program).

Representation
Permissions are displayed in a format like -rwxr-xr--, which is divided into three groups of three characters each:

Owner permissions (rwx): Read, write, and execute permissions for the owner.

Group permissions (r-x): Read and execute permissions for the group.

Others permissions (r--): Read permission for others.

Example
Let's look at an example of file permissions:

shell
-rwxr-xr--
-: File type (dash means a regular file)

rwx: Owner can read, write, and execute

r-x: Group can read and execute, but not write

r--: Others can only read

Commands to View and Set Permissions
ls -l: Lists files with their permissions.

chmod: Changes the file permissions.

Example: chmod 755 filename

Sets permissions to rwxr-xr-x

chown: Changes the file owner.

Example: chown user filename

chgrp: Changes the file group.

Example: chgrp group filename

Example Commands
Viewing Permissions

shell

ls -l
Output:

-rwxr-xr--  1 user group 1234 Jan  1 00:00 filename
Setting Permissions

shell

chmod 755 filename
This sets the permissions to rwxr-xr-x:

Owner: Read, write, execute

Group: Read, execute

Others: Read

Changing File Owner

shel
chown newuser filename
Changing File Group

shell
chgrp newgroup filename