Shell Scripting Tutorial-44: The 'passwd' File Explained Video Lecture | Shell Scripting: Discovering to Automate Command-Line Tasks - Back-End Programming

hello guys my name is Martin welcome to
my channel this is the 44th tutorial in
the series of tutorials on UNIX shell
scripting in this tutorial we're going
to talk about the p8 SS WD that is the
password file in the EDC folder in the
file system this is a very important
file and it consists of lot of useful
information about not just your account
but also the other accounts that the
operating system has and if there are
more than one users then the details of
all the users would be stored in this
file and we're going to check out the
output of a command that I am just going
to execute since this is a text file I
can use cat to see the output of this
file and remember you just have the read
permission to this file so you can view
the contents of the file but you cannot
make modifications to it right you have
to be the super user to do that and you
know it's sort of easy to get around
that problem but we're not going to do
that we don't want to mess with the
password file because it's very
important and the system uses it for you
know a lot of things so I'm going to
type in cat space the full path of the
file which is /e d c /p a double SW d
that's the name of the file and when I
press the Enter key you see that lot of
information pops up on my screen and on
the first line you would see that you
know information for the root user that
is a Super User is being displayed and
on the last line you would see
information about your ownself right so
since my name is motherhood and that's
my user name I'm seeing information
about my account on the last line of the
output right so there are seven fields
in each row in this text output and
we're going to discuss all these seven
fields the first field is a username
field right so since my name is mother
one who is being displayed and then the
P the first P will be is separated from
the second field with colon and the
second field shows a symbol X and that's
not just me but for all girls you would
see that the second line shows sorry the
second column shows the character X and
what this means is that the password for
all these user accounts is encrypted
and it's actually stored in another file
which is also in the PDC folder it's
called shadow and we don't even have
read permission to that file and you
know even if you would view the contents
of that file the passwords are encrypted
so you won't be able to gather much
information right so the first field is
for the username the second field is for
the password and the third field is the
user ID field it's also called UID and
you know you would see that UID for the
root user is zero and UID for you know
almost all the other user accounts is
greater than 100 right and you know this
is reserved root will always have the
user ID zero and also the group ID which
is the next field you know these two
entries will always be zero for the
super user and from 1 to 99 these user
IDs and group IDs are reserved for
predefined accounts right that are
created just when you install your
operating system and all user IDs
greater than 100 are allocated to system
accounts or groups that are created
after the operating system has been
installed right so that's the third and
the fourth key through the third field
is user ID and the fourth field is the
group ID the field add as you would see
in this output
tells me the name of my computer now how
would you know that I name my computer
the destruction due maybe I mentioned it
in this course may be attained but
anyway when you install your operating
system if you people remember while
installing Ubuntu you know during one of
the stages the Installer asks you to
provide a name to the operating system
and you know whatever name you type in
then if you type in your full name or if
you type in your contact number whatever
thing you type in it will be displayed
in the fifth field in the output of EDC
password right so I gave the name the
destruction - that's why I'm seeing that
here and the sixth field tells me my
home folder right and in this case my
home folder is a folder mother inside
the home directory in my file system and
I've opened my file system in the file
explorer here and you will see that
there is a directory called home and
I enter the home folder and if I
double-click on the holder mother inside
the home folder then you would see that
you know I basically see the same
content as I would see if I directly go
to places and click on the home folder
right so this is actually I mean what do
you see as an icon in the places tab you
know is actually a link to the home
folder that's within the file system
right so I hope you get the point
and the last field that you would see
that is the seventh field tells you the
default shell and you know it doesn't
just tell you the name of the shell it
also tells you the path right so there
is a file or you know a program in the
binary sorry in the BI and folder in my
file system that you know helps me
execute all the programs and it's called
bash and by stands for born again shell
and you would see that for some of these
entries you actually have SH as a Depot
shell and it's not really difficult to
change your default shell but you know
you don't have to really do that so
that's it for now I want to discuss this
file with you guys because we will be
doing some things in this course you
know that will need the information
about you know the contents of this file
and you will understand pretty soon but
for the time being I hope you had fun
watching this tutorial and this is a
very important file and make sure you
not mess with the permissions of this
file because if this file gets
accidentally deleted then your system
will stop working properly I don't think
it will work at all you know if you shut
it down and if you restart it then it
won't start you know that's what I think
I haven't ever done that and I would
suggest you guys not do that either and
even if you are in a playful mood please
stop yourself from doing that right that
can be dangerous so anyway thank you
guys for watching this tutorial I see
you guys the next one in which we will
discuss something important again so see
you later
and please subscribe to my channel