User Management - useradd, usermod & gpasswd commands

 user management:-

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creating a user with variants:

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#useradd -u <custom UID>  <username>   --> to create a user with different UID

ex: #usseradd -u 14000  half 

#useradd -c <description> <username>  --> to create a user with description

ex: #useradd -c mommy maa 

#useradd -g <primary group>  <username>   --> to create  a user with existing primary group

ex: #useradd -g kxip pbj

#useradd -G <seconadry group> <username>   --> to create a user and add the user to some secondary group

ex: #useradd -G tokyo red

#useradd -d <home dir>  <username>   -->> to create a user with different home dir

ex: #useradd -d /d1   public

#cd /d1 

#cp /etc/skel/.* /d1/

#useradd -s <shell path>  <username>   --> to create a user with diffferent shell path

ex: #useradd -s /bin/sh   blue

modifing  a users existing:-

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#usermod  -u <custom ID>  <username>   --> to change  UID of user

ex:#usermod -u 14500 half

#usermod -c <description>  <username>   --> to change the description

ex: #usermod -c mom maa

#usermod -g <primary group>  <username>  --> to change the primary group of user

ex: #usermod -g pbj pbj

#usermod -G <secondary group>  <username>  --> to change the user into secondary group

ex: #usermod -G csk  red

#usermod -d <home dir >  <username>  --> to change the home dir of user

ex: #usermod -d /home/blue   blue

#usermod -s <shell path>  <username>  --> to change the shell path of user

ex: #usermod -s /bin/bash  public

#usermod -l <new username>  <old user name>  --> to change the username of a user

ex: #usermod -l pub   public

#getent passwd public  --> no output

#getent passwd pub  --> to verify the username is changed

adding a  user to group:-

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#gpasswd -a <username>  <group name>   --> to add single user into group

ex: #gpasswd -a zafar pbj

#gpasswd -M <username1>,<username2>  <group name>   --> to add mmultiple users into a group (previously existing user will removed from that group)

ex: #gpasswd -M  zafar,maa,tokyo,blue   red

#getent group red  --> to verify the users added into the group

#gpasswd -A  <admin username>   <group name>  --> to make a perticulaar user  a admin of group

ex:#gpasswd -A zafar red

delete a user from group:-

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#gpasswd -d <username>  <groupname>   --> to delete a user from group

ex: #gpasswd -d tokyo red

#getent group red   -> to verify