Linux Processes
Viewing Processes
ps # view process that are running in the current shell ps -f # Displays PID
Display an entire list of processes across all terminals and including daemons
ps -ef
Some options to the ps command are not prefixed by a dash character; these are referred to as Berkeley-style options. The two most common of these are the a option, which lists all processes across terminals, and the x option, which lists processes that do not run on a terminal
ps ax ps -l
View Zombie Process
ps -el | grep Z
Top Command
press h key while in the top command to see a list of options
top
Killing Processes
Kill signal have many options; Kill followed by signal number then process ID
kill -1 5555
The KILLALL command uses the process name instad of the pid
killall -3 sample
Running Processes in the background
Add the & after the command to run in the background
samplescrpit &
Will run the script in the background and return the shell immediately back to the user
jobs # view the background job id
To kill a job id with the id number
kill -2 %1 # the %1 is the jobid number
After a background has been started you can move it to the foreground
fg %1 # the %1 is the jobid
You can pause a foreground process by CTRL Z
Nice command
You cannot change the PRI directly, but you can influence it indirectly by assigning a certain nice value to a process.
A negative nice value increases the likelihood that the process will receive more time slices, whereas a positive nice value does the opposite.
nice -n -20 ps -l # Starts the ps command with a nice value of -20
After a process has been started, you can change its priority by using the renice command and specifying the change to the nice value, as well as the PID of the processes to change.
To lower priority of the first two sample processes by changing the nice value from 0 to +15 and view the new values, you can execute the following commands:
renice +15 123 345