Linux Command Line Tutorial For Beginners 17 - file permissions; symbolic permissions and chmod Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development

hello guys welcome to the next video on
Linux command line tutorial for
beginners in this video we will see how
we can use while permissions in Linux
and especially we are going to talk
about symbolic permissions so in Linux
so let's get started first of all what
I'm going to do is I will just change
the directory to the desktop
and you can see here I have a file which
has a name file itself right so what I
want to do is I want to list the long
listing of this file so I will just do
LS minus L and press Enter and maybe in
the previous video also I have you know
just touched this topic that these thing
here is the permission for the file now
the first - on the left hand side you
can see - or - whatever you call it is
the type of file for example if it's
normal - it means it's a normal file if
it would be our D then it will be our
directory or if it would be a character
special file then it would be a C or it
would if it would be a B then it would
be a binary special file right now the
next three are you know group next we -
group or whatever next three element you
can say here is for the owner of the
file right and then next three is for
the group of the file so group contains
these rights and the last three is for
the permission is the permission for
everybody else right now the next you
can see here is one and one stands for
the symbolic links of the file so right
now we have only
link right now the next is this name
which is for the you know owner of the
file so the name of the owner of the
file is this one right next is the name
of the group of the file so this is for
the group now next is this one and this
is for the size of the file so right now
our file size is 22 and then next is the
date on which its created and then the
file name right so these are the
permissions so basically we are
interested in this area which is the
user group and other permissions and the
name of the user and the group right so
let's try to change the permission of
this file so there is a utility called
chmod which stands for change
mod to change the permission of the file
so for example I want to provide the
permission to the user also but first of
all what kind of permission we have so
for this file for example we have three
main kind of permission one is read
other is right and third one is
executable right so R stands for read W
stands for right and X stand for
executable so read right executable
permission for a file okay so for
example what I want to do is I want to
change the permission of others to
execute this file so I want to allow the
other persons to execute this file for
example right so what I can do is I will
just use CH mod which is the utility to
change the permission of the file and
then I can give the first of all name of
others so for example o stands for
others here
and then plus or minus plus is for
adding the permission and minus is for
subtracting the permission and then the
permission itself so I want to grant the
executable permission to the other user
so oh stands for other here plus is for
adding the permission and X for example
is the permission so executable
permission right and then the name of
the file itself so file right and
probable press ENTER here so permission
is chained and once again when we do LS
- L you can see here earlier the others
doesn't have the executable permission
but now the others have executable
permissions right next what we can do
here is once again we can change the
permission of others to write also so we
can do W here and then press ENTER and
once again we will do the long listing
and you can see the others can write and
execute and the read permission they
already had so they can now read write
and executable now it's not necessary
that you want to do this for in the
normal circumstances but this is just
for the example we want to so I want to
show you right so for example now I want
to change the permission of the group
and the group already have the
permission read and write write so I
want to change it to read write
executable so for the group once again
we will use ch mod and then for Group G
and then plus X so we will change the
permission of the group and the name of
the file and just press ENTER and then
long listing once again and you can see
now the group can also read write and
execute now for example once again I
want to you know reduce the permission
of the group once again so right now
group can read write and execute
I want to make it just to read so just
allow the group to only read the file so
once again CH mod and as I told you G is
for group and - is for reducing the
permission right so we want to remove
for example write and executable right
and then the name of the file and once
again when I press Enter and once again
when I do long listing now you can see
group can only read because we have
subtracted the you know permission of
the group to write and execute using
this notation okay now for example I
want to give the permission to everybody
so for example I want to give the user
of this file or owner of this file to
read write and execute and also I want
to give the give the group of this file
to read write and execute so what I can
do is here one more no gate notation I
can use which is for example chmod and
then the user is for the user and for
example I want to also change the group
so you can change the permission for
multiple you know robot user for example
you want to change it for user also and
for the group also so you can use this
combination also right and you can also
use equal to so which is for granting
the permission also so this notation is
also used to you know changing the
permission and I want to make it read
write and execute so I will just do read
write execute rwx for read write execute
okay so this will change the permission
of user or owner of this file and the
group of this file to read write and
execute and the name of the file don't
forget right and then plus
enter and once again we will do the long
listing and now we can see everybody
have read write and execute a
permissions right now for example I want
to remove the permission or change the
permission or to everybody right so for
example I want to remove the permission
for the user and the group and the
others so that they cannot even read
write or execute right so once again I
will do CH mod and what you can do is
you can do user group and the other you
can do the notation something like this
and then you can for example some do
something like - read write and execute
something like this okay and this will
remove the permission or otherwise you
can just do huge you can just use a for
all and then you can do - and then do
read write and execute right so a stands
for all so it stands for a user or owner
group and others so you are basically
want to subtract all the permission from
all the users and you can press Enter
before that we need to give the name of
the file press ENTER and then use long
listing and now we can see nobody has
the permission to you know change or
read write or execute this file right
now for example I want to give everybody
their permission back so I want to give
the same status I have in the you know
starting so I want to give the owner of
this file read and write group also read
and write and the others just read
permission so what I can do is I can do
chmod and for the user I want to add
once again the permission read and write
okay and then you can use the comma to
give the
others the permission for example group
and once again we want to give the
permission to the group read and write
or you can do this thing
something like read and write using
equals both are the same commands and
then for the others we want to just give
the read permission something like this
and the name of the file okay so use
comma in order to you know separate the
permission or if you want to chain the
multiple permission of the multiple
users right and plus enter and it gives
some problem let's see what's the
problem is yeah so the problem is chmod
is not spelled correctly
so I must correct it so I will remove
this a and now the command is normal
right so I will press enter and now once
again I will do the long listing and now
once again we have the normal permission
of the file so for owner
we have readwrite group we have
readwrite and for other we have read
permission so this is how you can change
the permission of a file using symbolic
notation so this our W or X is called a
symbolic notation right so this is how
you can change the permission I hope
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