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- In this video, I want to
explain Linux processes and jobs.

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Anything that runs on
Linux runs as a process,

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and processes have a process
ID, and they can be managed

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by sending signals to it.

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Signals are special operating
system instructions.

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There is Sigterm, also known as Signal 15,

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which is a default signal that
instructs a process to stop.

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There is Sigkill or Signal Nine,

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which is a signal to force a
process to stop immediately.

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I'll tell you how to do
that later in this lesson.

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Then there are jobs.

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Jobs are user processes
that have been started

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from a specific shell.

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And the nice thing about
jobs is that users can manage

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their own jobs.

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And all processes originate
as child from systemd.

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Let me make a drawing to show
you how this is organized.

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- In this video.

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I would like to explain a little bit

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about processes and how they
are hierarchically organized.

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So it all starts with systemd.

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Systemd is PID One.

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It's a model of all processes.

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And you will notice that all
other processes are a child

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of Systemd.

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You'll find kernel processes
between square brackets.

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If you use a command
like PSX, for instance,

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you'll find your service processes

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like your SSHD, and you'll
find many, many more.

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And then at some point, there
will be the gnome terminal.

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The gnome terminal is a process
that is typically started

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for a graphical terminal.

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And as a child of this known terminal,

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there is bash, and bash is your shell.

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Now, if in this shell
you are running commands,

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like a command, let's say, sleep 60,

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which will sleep for 60 seconds,

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or ls-l.

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All of these are children
of the bash shell.

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They are a part of the process tree.

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And because they are a
part of the process tree

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you can manage these as processes,

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but if they are your own,
then these are the one

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that can also be managed as jobs.

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In the next couple of lessons,

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I will show you how to
manage these processes

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as well as the jobs.