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The output of this command will appear as follows:
Figure 7.5: The output of the ps -l command
With the output of the 
ps -l
 command, notice the 
PRI
 and 
NI
 columns. 
PRI
 refers 
to the priority, and 
NI
 pertains to the "niceness" value, which we'll discuss in more 
detail later in this section. In this example, each process that I'm running has a 
PRI
 
of 
80
, and an 
NI
 of 
0
. I didn't change or alter any of these; these are the values that 
I get when I start processes with no special tweaks. A 
PRI
 value of 
80
 is the starting 
value for that value on all processes, and will change as we increase or decrease the 
niceness value.
As I mentioned, we have dedicated commands that allow us to alter priorities, 
nice
 and 
renice
. To determine which to use, it all comes down to whether or not 
the process is already running. With regard to the processes listed in 
Figure 7.5
, we 
would want to use 
renice
 to change the priority for those, since they're all already 
running. If we wanted to launch a process with a specific priority right from the 
beginning, we would use 
nice
 instead.
For example, let's change the process of the 
vim
 session I have running. Sure, this is 
a somewhat lame example, as 
vim
 isn't a very important process. In the real world, 
you'd be prioritizing processes that are actually important. In my case, since the 
vim
 
process has a PID of 
41267
, the command I would need to run in order to change the 
niceness would become this:
renice -n 10 -p 41267
The output of this command will appear as follows:
Figure 7.6: Changing the priority of a process with renice

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Chapter 7