Introduction to Linux in HPC/Users and permissions

Video

Linux Introduction Slides 67 - 88 (22 pages)

Slide Layout

   page 1: 
       Linux is a multi-user system.
       A user is logged in with an account and certain permissions.
   page 2: 
       Each file and directory has certain permissions.
       root has top permissions.
       Normal users may belong to multiple groups.
   page 3: 
       Read permission
       Write permission
       Execute permission for i) file and ii) directory
   page 4 - 12: 
       Example of ls -l (animation)
   page 13 - 16: 
       Permissions for user, group and other (animation)
   page 17: 
       chown to modify owner/group
       chmod to modify permission
   page 18: 
       Process is an instance of a program
       top and pstree
       Each process has permissions of that user.
       Each process has a unique ID (PID).
   page 19: 
       Start command in background command &.
       Ctrl-Z and bg
       fg brings a job to foreground.
   page 20 - 21: 
       Example of top (animation)
   page 22: 
       Single-letter commands for top

Quiz

Which command can prevent other users not in your group from writing to input.dat?

	chmod u-w input.dat
	chmod o-w input.dat
	chmod g-w input.dat