welcome to the video tutorial on
managing processes in Linux so what is
the process an instance of a program is
called the process in simple terms any
command that you give to your Linux
machine starts a new process for example
when you launch offers to write an
article it creates this process and it's
possible to have multiple processes aka
instances for the same program there are
two types of processes the first one are
the foreground processes they run on the
screen and need input from the user an
example of them are the office programs
the second one are the background
processes there are in the background
and usually do not need user input them
an example of them is the antivirus that
you use you can start a foreground
process either from the dashboard or you
can run it from the terminal so if you
want to run the badge your media player
you can go to - type in banshee and you
can run the media player this way
otherwise you can go to terminal and
type in banshee and execute the command
when using the terminal you will have to
wait until the foreground process runs
if you start a foreground process or a
program from the terminal then you
cannot work on the terminal till the
program is up and running to avoid such
a situation you can run the program and
send it to the background so that the
terminal remains available to you let's
learn how to do this for running a
process on the background you need to
start the program by typing in the
command main once execute the program
you need to present ctrl + Z then type
BG to send process to the background so
if we try the same on terminal we need
to put in the command name for the
process or the program and when it
starts running we need to press in ctrl
+ Z which will stop the process then we
need to type in BG to send the process
into the background
this way you can send the process to the
background and keep the terminal free
you can use the command FG to continue a
program which is stopped and bring it to
the foreground the simple syntax for
this utility is FG space the job name an
example for this s we will launch the
Banshee media player stop the process
and then we will type in FG to continue
the process on the foreground let's look
at some other important commands to
manage processes starting with top this
utility tells the user about all the
running processes on the Linux machine
the syntax for this utility is talked
so when we run this utility on the
terminal you would find a lot of fields
with different abbreviations which we'll
learn now one by one so starting with
the PID it is the process ID of each
task you can see here that it differs
for each task or a process the user is a
user name of the task owner so it can
vary from root to as many user accounts
that you have on your Linux system the
PR is the priority it can be 20 which
would be highest or minus 20 which would
be lowest and I is a nice value of a
task the VI RT that you read on the
screen is the virtual memory used it
shows memory in kilobytes the re s is
the physical memory used and it also
shows in kilobytes as h r is a shared
memory used and it also shows in
kilobytes the s is the status there are
five types of the same the first one is
d which says uninterruptible sleep
our is running s is sleeping T is traced
or stopped and the last one z is for
zombie the cpu percentage that you see
is the percentage of cpu time the
percentage of memory is the physical
memory used time plus tells us about the
total CPU time and the command is the
command name we will discuss some of
these fields in this tutorial the next
one is the PS utility this utility
stands for process status it is similar
to the task manager that pops up in a
Windows machine when we use ctrl + Alt +
delete this command is similar to the
top command but the information
displayed is different you can use these
in Texas with the PS command that is try
them so to check all the processes
running under a user you need to use
this command it will give us all the
information on processes and programs
running under guru 99 you can also check
the process status of a single process
by using the syntax PS space PID but
first we need to find the PID of a
process which we can do by typing in PID
of space the process name here we'll
type in Banshee and check its PID
so it says two seven eight three
so let's go ahead and check the process
status of this single process this is
how you can get information on the
status of a single process this command
terminate running processes on a Linux
system the syntax for the kill command
is kin space PID in order to use this
utility again you need to know the PID
of the process that you want to kill let
us try it with an example let's say we
have the Mozilla Firefox program running
on our system and we want to kill it
using the terminal for this you need to
find out the PID of the program Firefox
so now we know the PID of the program
Firefox let's go ahead and kill it if
the terminal does not return with an
error it implies that the program was
terminated successfully Linux can run a
lot of processes at a time which can
slow down the speed of some
high-priority processes and result in
poor performance to avoid this you can
tell your machine to prioritize
processes as per your requirements this
priority is called niceness and Linux
and it has a value between minus 20 to
19 the lower the niceness index the
higher would be the priority given to
that task the default value of all the
processes is 0 to start a process with
an iceless value other than the default
value you need to use the following
syntax
it says nice space - n then the nice
value then the process name if there's
some process already running on the
system then you can realize its value
using the syntax let us understand this
by an example so let us launch the
Banshee media player with a nice value
other than the default value which is
zero so here we have chosen 19 as a nice
value for this program now let us run it
now after cleaning the terminal with the
clear command we will now run the top
utility and check the niceness value of
the program Banshee so here we have the
Banshee media player and its niceness
value shows 19 now for realizing the
value of an already running process we
need to know it PID and as it shows here
the PID for the Banshee media player is
3 8 4 4 so let us go ahead and realize
its value from 19 to minus 20 for this
we need to type in sudo realize then the
new nice value which would be 20 here
then - P then the PID which was three
eight four four once we execute this
command sudo would ask for the password
upon entering the password terminal
would tell us that the nice value of the
process ID three eight four four has
been changed from 19 to minus 20 this is
how you can prioritize the processes
running on your Linux system and make it
more efficient moving on to DF utility
it suppose the free disk space on all
the file system the syntax says DF upon
running this utility we will see all the
file systems on our computer with the
used and the available disk space
if you want the above information in a
readable format then you can use the DF
utility with this option now you can see
the total size the used and the
available disk space on your computer
this command shows the free and the used
memory on the Linux system you can use
the arguments free space - M to display
output in megabytes or you can go with
free space - gene to display the output
in gigabytes let's try them so if we
type in free space - enemy we will see
that the total memory on the system is
one thousand two megabytes and out of it
860 megabytes have been used this is how
you can check the free and the used RAM
on your Linux system let us summarize
quickly any learning program or a
command given to a Linux system is
called a process a process could run in
foreground or background the priority
index of a process is called nice and
Linux its default value is 0 and it can
vary between 20 to minus 19 the lower
the niceness index the higher would be
the priority given to that task let us
go through the utilities as well
the BG command sends a process to the
background the FG command runs a stopped
process in foreground use top to get
details on all active processes PS gives
the status of processes running for
end-user PS space PID would give the
status of a particular process PID off
space process name gives the process ID
of the process or program kill space PID
terminates a process or a program nice
starts a program with a given priority
green eyes changes the priority of an
already running process DF would give
you the free hard disk space information
on your system and free because the free
Ram details
on your system thank you for watching
this tutorial I hope to see you in the
next one
you