List, set, and change standard ugo/rwx permissions

Context: RHCSA certification

List, set, and change standard ugo/rwx permissions

To manage file permissions on a Linux system, including the standard user/group/other (ugo) permissions, you can use commands like ls, chmod, and chown. Here's how you can list, set, and change standard ugo/rwx permissions:

1. List Permissions: To view the permissions of a file or directory, you can use the ls -l command. It displays the permissions in the long format, showing the user, group, and other permissions along with other file details.

   Example:

   ls -l myfile.txt

   The output will look something like this:

   -rw-r--r-- 1 user group 4096 Jun 1 10:23 myfile.txt

   The permission string -rw-r--r-- represents the user, group, and other permissions, respectively.

2. Set Permissions: To set the permissions explicitly using the chmod command, you can use the following format:

   chmod <permissions> <file>

   The <permissions> part can be represented using three digits or symbols:

   • Numeric representation: Each digit represents the permissions for user, group, and other respectively, with the values:
     • 4: Read (r)
     • 2: Write (w)
     • 1: Execute (x)
     • 0: No permission (-)

   Example:

   chmod 644 myfile.txt

   This command sets the permissions of myfile.txt to read and write for the owner (user) and read-only for the group and others.

3. Change Permissions: To change permissions using symbolic representation, you can use the following format:

   chmod <symbolic_permissions> <file>

   The <symbolic_permissions> part uses symbols to represent permissions:

   • u: User
   • g: Group
   • o: Other
   • a: All (user, group, and other)

   The symbols + and - are used to add or remove permissions, respectively. The permissions are represented using the symbols r (read), w (write), and x (execute).

   Example:

   chmod u+x myfile.txt

   This command adds executable permission to the user for myfile.txt.

Remember that changing file permissions should be done carefully, considering the security requirements and best practices for your system.