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Help Commands. Now what are the help commands that
are used in a Linux environment that will give you
some of the information or some help about other
commands. There are three types of help command
that are used in most of the Linux distributions.
The first one is whatis. So whenever you run a
command whatis followed by the command that you
want to inquire about, you will run whatis and
space then command. This will give you a quicker
a shorter version of the information about the
command that you're looking for. The next one we
have is the command whichever command you want to
run, let's say ls space and then --help.
This will give you a little bigger, a longer
version of the help, a bit more details about that,
the options about that command, and the last one is
man which is stands for manual, man space followed
by the command, the command name itself. When you
run that you will get a complete full listing of
the command descriptions to help about it. So now
let's look at our Linux machine and we'll see how
these commands work. So we are here in our Linux
machine. Let's do the clear, and we will find out
who we are. Again whoami, we are ourself, we type
clear. The first command that we learned, we're going to
run is whatis, it's all one word, space, let's say
ls. This will tell you that ls lists the
directory contents. The next one we will run is
whatis cd. That's what tells you the bash built-in
command. The CD is a bash built in command meaning
when you have a your Linux system installed, it
comes in as people's command. And what it does, it
changed the working directory from one directory
of course to another. Well, let's try the same
command to whatis pwd, tells you print name of
current working directory, return working directory
name. So why do we have two different answers for
one command is because we have two different
sources or two different dictionary already
installed, or you could say two different manual
pages installed on our Linux distribution.
There are, there could be more, there could be 2, 3, 4,
or 5, depending on what type of command it is
and what kind of description it has. Let's look at
the next command. Let's say ls --help.
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See, there you go. It gives you a little longer
description of your ls command. And it tells you
all the different options that are associated with
ls command. So of course right here, that's where
it starts, and it goes all the way down, it tells you
-a option, -A uppercase option, and so on.
We could also run chmod --help. Remember
chmod command is the change mode command to
change the permission of a file. So when we do
help, we're going to see it tells you, gives you
quick description starting from here. It tells you
that change the mode of each FILE to that of RFILE.
Change the mode of each FILE to MODE, and a few
different options. Same thing you run this command
with other different command --help,
it will give you the information
about that command. Now the last one we're going
to look at is the man command. man stands for
manual and then space, let's say ls, and you run
this command. There you go. It will give you a
very nice descriptive way, a nice formatted way of
for the user command information, tells you the
name, the synopsis, the description and each
option of the command. You could do space to go on
each page, hit spacebar spacebar every time you
want to quit out, just hit Q and you're going to be
out of it. Same thing when you do a man command
and then pwd, you do enter, and you're going to see
the exact same thing. pwd print name of the
current working directory and what other options
it has. My favorite command, in all those help
commands is this man command because it has
exactly the information, the detailed information of each command.
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