Difference between revisions of "Linux-for-Sys-Ads/C2/Modifying-User-Account/English"

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|| The '''command usermod''' is used to modify the '''attributes''' of an already created '''user account'''.
 
|| The '''command usermod''' is used to modify the '''attributes''' of an already created '''user account'''.
  
−
This is the syntax
+
This is the syntax.
  
−
Here the '''options''' part is not mandatory
+
Here the '''options''' part is not mandatory.
  
 
This '''command''' supports many '''options'''.
 
This '''command''' supports many '''options'''.
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|-
 
|-
 
|| Press Ctrl+Alt+T
 
|| Press Ctrl+Alt+T
−
|| Open the '''Terminal '''by pressing '''Ctrl, Alt and T '''keys simultaneously on the keyboard.
+
|| Open the '''terminal '''by pressing '''Ctrl, Alt and T '''keys simultaneously on the keyboard.
 
|-
 
|-
 
||  
 
||  
Line 62: Line 62:
 
|-
 
|-
 
|| Highlight # prompt
 
|| Highlight # prompt
−
|| Notice, our '''login prompt '''has now changed to''' '''a '''hash''' symbol.
+
|| Notice, our '''login prompt '''has now changed to a '''hash''' symbol.
  
 
This indicates that we are in the''' root user mode'''.
 
This indicates that we are in the''' root user mode'''.
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|| In order to modify '''user ID''' to '''1100''',  
 
|| In order to modify '''user ID''' to '''1100''',  
  
−
On the terminal we have to type-
+
On the '''terminal''' we have to type-
  
 
'''usermod space hyphen u in small letter 1100 radha'''
 
'''usermod space hyphen u in small letter 1100 radha'''
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Type: addgroup electronics [Enter]
 
Type: addgroup electronics [Enter]
−
|| Switch to the terminal
+
|| Switch to the '''terminal'''.
  
 
Type '''addgroup space electronics'''
 
Type '''addgroup space electronics'''
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addgroup literature_club [Enter]
 
addgroup literature_club [Enter]
−
|| Next, type '''addgroup space literature_club'''
+
|| Next, type '''addgroup space literature_club'''.
 
|-
 
|-
 
|| Show the output
 
|| Show the output
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|| '''hyphen capital G''' option removes the '''user''' from previous '''supplementary groups'''  
 
|| '''hyphen capital G''' option removes the '''user''' from previous '''supplementary groups'''  
  
−
In this case, it removes from the previous supplementary groups
+
In this case, it removes from the previous '''supplementary groups'''.
 
|-
 
|-
 
|| Highliture literature_club
 
|| Highliture literature_club
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|| And adds the '''user''' to the new '''group''' '''literature_club'''
 
|| And adds the '''user''' to the new '''group''' '''literature_club'''
 
|-
 
|-
−
|| Execute at the terminal:
+
|| Execute at the '''terminal''':
  
 
id radha [Enter]
 
id radha [Enter]
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Add a '''user''' to a new '''supplementary group'''
 
Add a '''user''' to a new '''supplementary group'''
 
|| How can you add a '''user''' to a new '''supplementary group''' while retaining the previous '''groups'''?
 
|| How can you add a '''user''' to a new '''supplementary group''' while retaining the previous '''groups'''?
−
* For this, you should use '''-a '''option.
+
* For this, you should use '''-a option.'''
 
* '''a option''' denotes '''append'''.
 
* '''a option''' denotes '''append'''.
  
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|| Execute at the terminal:
 
|| Execute at the terminal:
 
id radha [Enter]
 
id radha [Enter]
−
|| Once again type '''id space radha'''
+
|| Once again, type '''id space radha'''
 
|-
 
|-
 
|| Show the output
 
|| Show the output
−
|| Notice that '''user radha''' now belongs to two '''supplementary groups'''
+
|| Notice that '''user radha''' now belongs to two '''supplementary groups''' -
  
 
'''music_club''' and '''literature_club'''
 
'''music_club''' and '''literature_club'''
 
|-
 
|-
 
|| usermod -l testmod radha
 
|| usermod -l testmod radha
−
|| Suppose we now want to''' '''change the '''login name''' itself from '''radha''' to '''testmod'''.
+
|| Suppose we now want to change the '''login name''' itself from '''radha''' to '''testmod'''.
  
 
To do this, on the '''terminal '''type the following:
 
To do this, on the '''terminal '''type the following:
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|-
 
|-
 
|| Back to '''terminal'''.
 
|| Back to '''terminal'''.
−
|| Press Ctrl C to stop the currently running process.
+
|| Press '''Ctrl C''' to stop the currently running process.
 
|-
 
|-
 
|| Press Up key
 
|| Press Up key
  
 
Press Enter
 
Press Enter
−
|| Press the '''Up''' arrow key until you get the previous '''grep command'''.
+
|| Now press the '''Up''' arrow key to get the '''grep command''' for '''user testmod'''.
  
 
And press '''Enter.'''
 
And press '''Enter.'''
 
|-
 
|-
 
|| Show output
 
|| Show output
−
|| Notice that we have '''testmod''' as the new '''home directory '''for '''user testmod'''.
+
|| Notice that we have '''testmod''' as the new '''home directory '''for the '''user testmod'''.
 
|-
 
|-
 
|| Slide 8
 
|| Slide 8
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|-
 
|-
 
|| Press Up key  
 
|| Press Up key  
−
|| Press the '''Up''' arrow key to get previous '''grep''' command.
+
|| Press the '''Up''' arrow key to get previous '''grep command.'''
 
|-
 
|-
 
|| Highlight shell and comments filed in the output
 
|| Highlight shell and comments filed in the output
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It will prevent the '''user''' from '''logging in''' from any other source including '''ssh'''.
 
It will prevent the '''user''' from '''logging in''' from any other source including '''ssh'''.
  
−
I will skip the demonstration of this command.
+
I will skip the demonstration of this '''command'''.
 
|-
 
|-
 
|| usermod -U testmod [Enter]
 
|| usermod -U testmod [Enter]
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Press Enter
 
Press Enter
−
|| Once again check the contents of '''/etc/shadow''' file
+
|| Once again check the contents of '''/etc/shadow''' file.
  
 
Notice, the '''exclamation mark''' is removed now.  
 
Notice, the '''exclamation mark''' is removed now.  

Latest revision as of 11:38, 15 February 2019

Title of script: Modifying User Account

Author: Antara Roy Choudhury

Keywords: usermod, change, lock password, unlock password, lock account, unlock account, change home directory, change shell, change comments

Visual Cue Narration
Slide 1: Introduction Hello and welcome to the spoken tutorial on Modifying User Account in Linux.
Slide 2: Learning Objectives In this tutorial we will learn about
  • usermod command
  • Modifying attributes of user account
  • Locking and unlocking password or account

We will do this through some examples.

Slide 3: System requirement To record this tutorial, I am using Ubuntu Linux 16.04 OS
Slide:4 Prerequisite To practice this tutorial,
  • you should have gone through the Linux System Administration tutorials on this website and
  • you must have root access to your computer.
Slide 5: The command usermod is used to modify the attributes of an already created user account.

This is the syntax.

Here the options part is not mandatory.

This command supports many options.

We will learn them through some examples.

Retain same screen Earlier in the series, we had created a user radha.

Now let’s modify the user account attributes of radha by using the usermod command.

Press Ctrl+Alt+T Open the terminal by pressing Ctrl, Alt and T keys simultaneously on the keyboard.

Type sudo su [Enter]

First, we will login as superuser or root user.

To do so, type sudo space su and press Enter.

Type Password of your account [Enter] Type your password and then press Enter.
Highlight # prompt Notice, our login prompt has now changed to a hash symbol.

This indicates that we are in the root user mode.

Only narration Here onwards, please remember to press the Enter key after typing each command.
Type at the terminal:

id radha

[Enter]

We will check the user id and group information for user radha.

On the terminal type id space radha

Show the output Notice, user ID of radha is 1002


usermod -u 1100 radha [Enter]

In order to modify user ID to 1100,

On the terminal we have to type-

usermod space hyphen u in small letter 1100 radha

Execute at the terminal: id radha [Enter] Now once again, type id space radha.

Notice that the UID has been changed to 1100.

usermod command can be used to modify a user’s primary and supplementary group.
Highlight the output of previous command User radha belongs to primary group CSE

And supplementary groups music_club and sports_club.

Slide 6A
  • We will change the primary group from CSE to electronics.
  • We will also change the supplementary group to literature_club.
Slide 6B
  • But we have not created the groups electronics or literature_club.
  • So, first we have to create these two groups.

Type: addgroup electronics [Enter]

Switch to the terminal.

Type addgroup space electronics

Show the output Group electronics is added with GID 1006.
Type

addgroup literature_club [Enter]

Next, type addgroup space literature_club.
Show the output Group literature_club is added with GID 1007.
usermod -g electronics -G literature_club radha

[Do not press Enter]

Now, to modify the primary and supplementary groups, type:

usermod space -g space electronics space -G in caps space literature_club space radha

Highlight music_club and sports_club of the output of previous command hyphen capital G option removes the user from previous supplementary groups

In this case, it removes from the previous supplementary groups.

Highliture literature_club

[Now press Enter]

And adds the user to the new group literature_club
Execute at the terminal:

id radha [Enter]

Type id radha
Show the output

Highlight appropriately

Now we can see that the primary group is set to electronics.

And supplementary group is set to literature_club.

Slide 7:

Add a user to a new supplementary group

How can you add a user to a new supplementary group while retaining the previous groups?
  • For this, you should use -a option.
  • a option denotes append.

usermod -a -G music_club radha [Enter]

Say for example, user radha wishes to be in both music_club and literature_club groups.

For this type:

usermod space hyphen a space hyphen G in caps space music_club space radha

Execute at the terminal:

id radha [Enter]

Once again, type id space radha
Show the output Notice that user radha now belongs to two supplementary groups -

music_club and literature_club

usermod -l testmod radha Suppose we now want to change the login name itself from radha to testmod.

To do this, on the terminal type the following:

usermod space hyphen l space testmod space radha

Now user radha has become user testmod.
grep testmod /etc/passwd Let’s search for testmod’s details in /etc/passwd file.

Type grep space testmod space /etc/passwd

Highlight appropriately Notice that the login name or user name has changed but the home directory remains the same.

Ideally, we should rename the home directory to match the login name.

There are 2 methods to do this.
Method 1:

We can manually rename the home directory to match the login name.

Let me do that now.

Type mv /home/radha /home/testmod

[Enter]

Type mv space /home/radha space /home/testmod

This command will rename directory radha to testmod.

Type gedit /etc/passwd & [Enter] Now, use any text editor to update the entry in /etc/passwd file.

I will be using gedit text editor.

Type gedit space /etc/passwd space ampersand

Modify /home/radha to /home/testmod Now search for /home/radha

Replace it with /home/testmod

Click to save >> close the file Save and close the file.
Back to terminal. Press Ctrl C to stop the currently running process.
Press Up key

Press Enter

Now press the Up arrow key to get the grep command for user testmod.

And press Enter.

Show output Notice that we have testmod as the new home directory for the user testmod.
Slide 8 Method 2:

We can change the home directory for the user radha with the help of usermod command.

Slide 8 The syntax to change the home directory of user radha to the directory named testmod is as follows:

usermod space -m space -d space /home/testmod space radha

This command will change the home directory of user radha to testmod
Slide 8
  • -d is used to modify the directory for any existing user account
  • -m moves the contents of the existing home directory to the new home directory.

The new directory will be created, if it does not already exist.

Slide 8 Important note:

We should write hyphen d option immediately after the new directory name.

Else we will get an error.

I will not demonstrate this because we have already changed the home directory using method 1.
Now let’s learn how to modify the user’s login shell and comments field.
Highlight output of previous command Notice that our current login shell is /bin/bash and we have “Radha” as comments.
Type:

usermod -s /bin/sh -c "This is modified user" testmod [Enter]

On the terminal type

usermod space hyphen s space /bin/sh space hyphen c space within double quotes This is modified user space testmod

Press Up key Press the Up arrow key to get previous grep command.
Highlight shell and comments filed in the output Notice, we have changed the values in shell and comments field.

usermod -L testmod

As a system admin you may need to lock a user account for various reasons, like violation of some rules by the user.

To lock the user testmod, type:

usermod space hyphen L in Caps space testmod

cat /etc/shadow [Enter] Now type cat space /etc/shadow
On doing so, we get an exclamation mark added before the encrypted password for user testmod.

So, no password will match it anymore.

We have also seen this while locking password with passwd command.

Slide 9
  • It will lock only the access to password.
  • If you wish to lock the account itself, you should also set the expiry date to 1.
Slide 10 For that type

usermod space hyphen capital L space hyphen e space 1 space username

It will prevent the user from logging in from any other source including ssh.

I will skip the demonstration of this command.

usermod -U testmod [Enter] To unlock the account we have to type:

usermod space hyphen U in caps space testmod

Press Up key twice

Press Enter

Once again check the contents of /etc/shadow file.

Notice, the exclamation mark is removed now.

It means the password is not locked.

Retain same screen We have seen all the options supported by usermod command.

You can use the man command anytime to get details of usermod command.

Type man usermod [Enter] Type man space usermod
Show the output

And scroll down

Notice, all the details about this command as shown.

Type q to quit from this command.

Type exit and press Enter To exit from the root user access, type exit

And press Enter.

Retain same screen This brings us to the end of this tutorial.

Let us summarize.

Slide 11 Summary In this tutorial we learnt about-
  • usermod command
  • Modifying attributes of user account
  • Locking and unlocking password or account
Slide 12 As assignment, modify user account amit such that
  • Primary group is electronics
  • Supplementary groups are music_club and literature_club
  • Set home directory as amit_newDir
  • Include comment "Stream Change Student"
Slide 13
  • Perform all the mentioned tasks in a single command.
  • Check the entry of user account amit in /etc/passwd and /etc/group files
Slide 14

About Spoken Tutorial project

The video available at the following link summarises the Spoken Tutorial project.

Please download and watch it.

Slide 15

Spoken Tutorial workshops

The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates.

For more details, please write to us.

Slide 17

Forum for specific questions:

Pls post your timed queries in this Forum.
Slide 18

Acknowledgement

Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

The script has been contributed by Antara

And this is Praveen from IIT Bombay signing off.

Thanks for joining.

Contributors and Content Editors

Nancyvarkey, Pravin1389

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