Lesson 1

Date: 1/22/2014
User accounts, files and directories, processes, system commands.
Linux for Engineering and IT Applications


Processes

  • Program running on a system is a process. Linux is a multi-processing (multi-tasking) system.

  • Attributes: Lifetime, PID, PPID, UID, GID, env variables, CWD.

  • Process with PID=1 is init

  • Monitoring: ps (for full listing, use ps -ef or ps -aux) top, pstree

  • Signal a running processes with PID=1009: 
        kill -HUP 1009    #Hang up; re-read config files
    kill -1   1009
 
    kill -9  1009     #Kill; stop unconditionally
    kill -KILL 1009

    kill -15   1009    #Terminate gracefully
    kill -TERM 1009

    kill -TSTP 1009   #Suspend; can be continued
    kill -18   1009

  • Process can be started with lower and higher priority through nice
    (range: -20 highest, +19 lowest) 
        nice 10 matlab
  • Process can be re-niced at run time: 
        renice 5 1009
  • Suspend interactive process and move it to the background: Ctrl-Z 
      jobs
  bg %1
  jobs
  • Move a background process to the foreground: 
     fg %1


    • Take me to the Course Website