Introduction to Linux in HPC/Users and permissions

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Introduction to Linux in HPC/Users and permissions /
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Video

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


Info:  no tips in this section


Warning:  no warnings in this section


Exercises in Terminal (slide 89)

1. Create an empty file, make it read-only, make it executable.
2. Start a process (e.g. sleep 10m)
3. Start a process, bring it into background/foreground.