Linux 13 - Create, Monitor and Kill Processes

• background and foreground
• persistent processes
• interact with processes
• sort running processes in top

Background and Foreground

# sleep 1000

• captures the terminal and sleeps for 1000 sec
  • to run in bacground add & to the end
    • this wil give back control of terminal
• to access programs from background use jobs commands
• typing fg <job number> will bring it into foreground
• to put something in the background you can suspend the process by
  • CTRL+Z
  • jobs command will show it as suspended
  • to un-suspend the process but still keep it in the background
    • use command bg <job number>
• If jobs are running in the background you can interact with them as long as the terminal windows is open
  • Once closed the only way to terminate a job is with
    • kill follwed by the PID
    • kill has two main ways to kill a process
      • kill -l 15 // TERM
      • kill -l 9  //  KILL
• by default kill will use 15. 15 is a nice way to kill the prcoesses
• by using 9 we risk having orphaned processes in the system

Persistent Processes
A process that still runs even after the user logs off

# nohup sleep 1000 &
[1] 3029
# nohup: ignoring input and appending output to `nohup.out'

nohup is meant to "run a program immune to hangups"

Interact with processes
top

- similar to task manager in windows
- by default it will sort by CPU usage

by pressing the h key (help) it will show us the different arguments it can have

by using the < and > keys we can sort by different catogries

to kill a process
by default Kill PID 3420 with signal [15]:

uptime
- presents system uptime, logged-in users, load average in 1, 5 and 15 minute intervals

# uptime
01:44:40 up 1:08, 2 users, load average: 0.00, 0.00, 0.00

average is in intervals of 1 minute, 5 minutes, 15 minutes

free
- presents free, used, total, cached, swap system memory

---