View source for Linux-for-Sys-Ads/C2/Assigning-groups-on-user-creation/English-timed

{| border=1
|-
|| '''Time'''
|| '''Narration'''

|-
|| 00:01
|| Hello and welcome to the spoken tutorial on '''Assigning Groups '''on''' User Creation '''in''' Linux.'''

|-
|| 00:08
|| In this tutorial we will learn about

Creating a''' user group''' '''/etc/group file'''

|-
|| 00:17
||Assigning''' groups '''to '''users '''at the time of''' account creation'''

|-
|| 00:22
||We will do this through some examples.
|-
|| 00:25
|| To record this tutorial, I am using '''Ubuntu Linux 16.04 Operating System'''
|-
|| 00:32
|| To practice this tutorial, 

you should have gone through '''Linux System Administration '''tutorials''' '''on this website.

|-
|| 00:40
||you must have '''root access''' to your computer.

|-
|| 00:44
|| What is a '''group '''in''' Linux'''?

|-
|| 00:47
||We can understand '''group''' as a '''collection of users'''.

|-
|| 00:51
||In a college system, a '''group '''can be '''different departments''' like '''CSE''', '''Electrical''' etc.

|-
|| 00:58
||'''Groups''' can also be different clubs like '''music club''',''' sports club, literature club,''' etc.

|-
|| 01:06
|| '''Linux''' supports two types of '''groups'''.

'''Primary group '''and''' '''  '''Supplementary group '''

|-
|| 01:12
|| Every '''user''' must belong to one and only one''' primary group'''.

|-
|| 01:17
||This is the default''' group''' for the '''user''' when the '''user '''logs in. 

|-
|| 01:22
||For example: a student must belong to one and only one '''department'''.

|-
|| 01:28
|| A '''user''' can be a member of more than one '''group'''. 

|-
|| 01:32
||Those '''groups '''are called '''supplementary groups'''.

|-
|| 01:36
||These '''groups '''are assigned to the '''user''', to provide him additional '''access''' to resources.

|-
|| 01:43
||More on '''access''' mechanism or '''permission''' will be discussed in subsequent tutorials. 
|-
||01:50
|| Let’s take an example. '''User radha '''belongs to the '''CSE department'''.

|-
|| 01:56
||She is also a member of the '''music club '''and '''sports club'''.

|-
|| 02:01
||In this scenario, '''CSE''' is the '''primary group '''for '''radha'''.

|-
|| 02:05
||And she is a member of two '''supplementary groups '''- '''music club '''and '''sports club'''.

|-
|| 02:12
||Let’s create this scenario in our system.
|-
|| 02:16
|| First, we will create '''group CSE'''.

|-
|| 02:19
||And we will use '''addgroup command '''in order to create this '''group'''.
|-
|| 02:24
|| Open the '''Terminal '''by pressing '''Ctrl, Alt and T '''keys simultaneously on the keyboard.
|-
|| 02:32
|| Now, we should login as '''superuser '''or '''root user'''.

|-
|| 02:37
||To do so type: '''sudo space su '''and press '''Enter.'''
|-
|| 02:44
|| Type the admin '''password '''and then press '''Enter'''.
|-
|| 02:48
|| Notice, our '''login prompt '''has changed to''' '''a '''hash''' symbol.

|-
|| 02:53
||This indicates that we are in the '''root user '''mode.
|-
|| 02:57
|| Here onwards, please remember to press the '''Enter''' key after typing each '''command'''.
|-
|| 03:03
|| Now type '''addgroup space cse'''
|-
|| 03:08
|| This will create '''group cse'''.

|-
|| 03:12
||'''Linux''' automatically allocates a '''Unique ID''' for each '''group''' that is created.

|-
|| 03:18
||Here, '''GID, '''that is '''Group ID''' is '''1002'''.
|-
|| 03:22
|| Alternatively, we can mention a '''GID '''of our choice.

|-
|| 03:28
||For this, we need to use '''hyphen gid''' option along with the '''addgroup command'''.

|-
|| 03:35
||'''GIDs''' in the range of''' 0 '''to''' 999''' are '''reserved''' for the '''system users'''.

|-
|| 03:42
||So, always choose a number greater than or equal to '''1000''' as '''GID'''

|-
|| 03:49
|| Let’s us create a '''group Music_club''' with the''' GID 1012.'''
|-
|| 03:55
|| On the '''terminal '''type:

'''addgroup space hyphen gid 1012 space Music underscore club '''

|-
|| 04:06
||Here type '''M''' is in '''capital letter.'''
|-
|| 04:10
|| Notice, it is showing some error.

|-
|| 04:13
||Actually, we should have written '''m '''in '''lowercase '''letter'''.'''

Let’s try that.
|-
|| 04:19
|| Press the '''Up''' arrow key to get the previously executed command. 
|-
|| 04:24
|| Change '''capital M''' to '''m''' in '''lowercase''' letter.
|-
|| 04:30
|| The '''command''' is working now.

|-
|| 04:32
||So, always remember to use '''lowercase '''letters while writing '''group '''names. 
|-
|| 04:38
|| Similarly let’s create another '''group sports underscore club'''.

|-
|| 04:43
||This time no need to mention the '''GID'''.
|-
|| 04:48
|| Now we have three groups '''cse, music underscore club '''and''' sports underscore club'''.
|-
|| 04:55
|| How can we check the details of the created '''group'''?

Type '''cat space /etc/group'''
|-
|| 05:05
|| There will be an entry in this file for every '''user''' on the '''system.'''
|-
|| 05:11
|| Each line has four '''fields''' separated by a '''colon '''symbol.

|-
|| 05:16
||The first '''field''' is the name of the '''group.'''

|-
|| 05:19
||The second '''field''' is the '''encrypted password''' for the '''group'''.

|-
|| 05:24
||Third '''field''' shows the '''GID '''as a number.
|-
|| 05:28
|| Fourth '''field''' contains the list of '''users''' that belong to that '''group '''separated by '''commas'''.

|-
|| 05:35
||This list contains all '''users''' who have this '''group''' as a '''secondary group.'''
|-
|| 05:41
|| We can see the entries for '''cse, music underscore club''' and '''sports underscore club groups.'''

|-
|| 05:49
||Notice, '''music underscore club''' has '''Gid 1012 '''which we mentioned during '''group '''creation.

|-
|| 05:57
||Here, the fourth '''field '''is empty for all the '''groups'''.

|-
|| 06:02
||This is because there are no members in these '''groups''', as of now.

|-
|| 06:07
||The '''password field '''is '''x'''. 

|-
|| 06:10
||We will discuss about the '''password field '''and list of members '''field '''in detail, in a separate tutorial on '''groups'''.
|-
|| 06:18
|| Now, how can we specify the '''primary '''and''' supplementary groups''' while creating the '''user'''?

Let us see an example.
|-
|| 06:26
|| To specify that '''user radha '''belongs to the '''primary group cse''', type:

'''adduser space hyphen ingroup space cse space radha '''
|-
|| 06:40
|| Type the '''password '''as '''pass underscore radha''' and press '''Enter.'''

|-
|| 06:46
||Retype the same password and press '''Enter.'''

|-
|| 06:50
||Type name as '''Radha''' with '''capital R'''.

And proceed as we have done before.
|-
|| 06:59
|| We have successfully created '''user radha''' with '''primary group cse'''.
|-
|| 07:05
|| So, you should use '''ingroup option''' to specify''' primary group'''’s name while creating the '''user'''.
|-
|| 07:13
|| As we know, '''radha''' is a member of '''music underscore club'''.

|-
|| 07:17
||So '''music underscore club''' will be the '''supplementary group''' for the '''user radha.'''

|-
|| 07:23
||Type '''adduser space radha space music underscore club'''
|-
|| 07:31
|| Remember. 

To add '''supplementary groups''' using '''adduser command''', you should have an existing '''user'''.
|-
|| 07:38
|| Here, we have first created the '''user radha.''' Then added '''radha''' to the '''supplementary group''' using '''adduser command.'''
|-
||07:46
|| If you need to specify that '''radha''' is also a member of '''sports club '''type: 

'''adduser space radha space sports underscore club'''
|-
|| 07:59
|| Let’s check '''user radha'''’s details using '''id command'''.

|-
|| 08:04
||Type '''id space radha'''
|-
|| 08:08
|| Notice, '''User radha''' is in group '''cse''' which has '''GID''' 1002

|-
|| 08:15
||That is the''' primary group''' for '''radha'''.

|-
|| 08:19
||Next, there is the list of '''groups''', where '''user radha '''is member of.

|-
|| 08:25
||Along with '''primary group cse, radha''' is also a member of two '''supplementary groups music underscore club''' and '''sports underscore club.'''
|-
|| 08:35
|| Now let’s check our '''/etc/group file''' for the entry of '''radha'''

|-
|| 08:42
||Type: '''grep space radha space /etc/group'''
|-
|| 08:49
|| Notice, you can see '''user radha''' is the member of '''groups music underscore club''' and '''sports underscore club'''

|-
|| 08:58
||But not as a member of the '''primary group''' that is '''cse'''.

|-
|| 09:03
||So the '''group file''' will list only the''' supplementary groups''' in which the '''user''' is associated.
|-
|| 09:10
|| Check the '''/etc/passwd file''' for the details of the '''username radha.'''

|-
|| 09:17
||Type '''grep space radha space /etc/passwd'''
|-
|| 09:25
|| Notice, the fourth '''field''' is '''1002'''

|-
|| 09:29
||It is the '''GID''' for the '''group cse'''.

|-
|| 09:33
||It is the '''primary group''' for '''radha.'''
|-
|| 09:36
|| So, remember '''/etc/passwd''' shows '''primary group ID '''for a '''user'''

|-
|| 09:43
||'''/etc/group file''' shows list of '''usernames''' who have the''' group '''as a '''supplementary group'''

|-
|| 09:51
|| Command '''id space username''' shows the details of both''' primary '''and''' supplementary groups'''
|-
|| 09:59
|| You can also specify the '''group id''' instead of''' group'''’s name while creating the '''user'''.

|-
|| 10:05
||Let us create a '''user suraj''' and assign him to the '''group cse''' using the '''gid'''.

|-
|| 10:12
||We know''' group cse''' has '''GID 1002''' 
|-
|| 10:17
|| So type: '''adduser space hyphen gid space 1002 space suraj'''

|-
|| 10:26
||You should use '''hyphen gid option''' to specify the '''group ID'''.

|-
|| 10:32
||Use '''pass underscore suraj''' as the '''password'''

|-
|| 10:37
||Retype the '''password'''

Full Name as '''Suraj''' with '''S''' in capital letter.

|-
|| 10:45
||Proceed as we have done for the previous '''users'''.
|-
|| 10:49
|| We have successfully created '''user suraj '''with '''primary group cse.'''
|-
|| 10:55
|| To exit from the '''root user access''', type '''exit'''
|-
|| 11:00
|| This brings us to the end of this tutorial.

Let us summarize.
|-
|| 11:05
|| In this tutorial we learnt about-

Creating''' primary group'''
|-
|| 11:10
||Assigning '''user '''to the '''primary group'''

|-
|| 11:13
||Assigning''' user '''to the '''supplementary group'''  '''/etc/group file'''

|-
|| 11:19
||Assigning''' groups '''to''' users '''at the time of''' account creation'''

|-
|| 11:24
|| As an assignment- Create two '''groups: ''' '''cultural ''', '''literature'''

|-
||11:30
||Now create a''' user ajay''' with '''Home directory''' as '''/home/ajay underscore dir '''

|-
|| 11:39
||'''User id '''as''' 1090'''

|-
|| 11:42
||'''Primary group '''as '''cultural'''

|-
|| 11:45
||'''Supplementary group '''as '''literature'''

|-
|| 11:49
||Add '''comments "Native: Mumbai"'''
|-
|| 11:52
||  Use the '''command id''' to check the '''user '''details

|-
|| 11:56
|| Check the details of '''user ajay '''in '''/etc/passwd '''and '''/etc/group files'''
|- 
|| 12:05
|| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.
|- 
|| 12:13
|| The Spoken Tutorial Project team conducts workshops and gives certificates.

For more details, please write to us.
|-
|| 12:23
|| Please post your timed queries in this forum.
|- 
||12:27
|| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

|- 
|| 12:33
|| The script has been contributed by Antara and this is Praveen from IIT Bombay signing off.

Thank you for joining.
|-
|}