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Abhishek Pathak
Abhishek Pathak

Posted on • Edited on

Linux User and Group Management

#linux #ubuntu

Create new user

Linux daddy will guide you.

sudo adduser username
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You are now a daddy

sudo useradd username
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useradd

Check all the users 

sudo cat /etc/shadow
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etc shadow

Consider,
abhishek2:!:19579:0:99999:7:::

The row is split into 9 fields seperate by :

Each field resembles as:

  1. Username. User account and login name that exist in the system.
    1. Encrypted password. Password using the format $type$salt$hashed and eight to 12 characters long.
    2. Last password change. Date since Jan. 1, 1970, when the password was last changed.
    3. Minimum password age. The minimum number of days that must elapse before the password can be changed by the user.
    4. Maximum password age. The number of days after which the password must be changed.
    5. Warning period. The number of days before the password expires, during which time the user gets a warning to change the password.
    6. Inactivity period. The number of days post-expiration -- since Jan. 1, 1970 -- before the user's account is disabled.
    7. Expiration date. The date on which the account was disabled.
    8. Unused. This field is left empty and reserved for future use

User with custom shell 

sudo useradd -s /bin/bash abhishek
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  • /bin/bash -> env shell

User with own home directory 

sudo useradd -m -d /home/abhishek abhishek
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  • /home/abhishek4 -> this can be any path

User with comment 

sudo useradd -c "user name is abhishek" abhishek
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User with the account expiery date 

useradd -e 2023-08-32 apple
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  • -e -> The date on which the user account will be disabled. The date is specified in the format YYYY-MM-DD.

User with custom userId 

sudo useradd -u 1822 abhishek
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Change default home directory of user geet 

usermod -d /var/tmp/user/geet -m geet
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Change login name of user geet 

sudo usermod -i geet GEET
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Change default shell of user geet 

usermod -s /bin/fish geet
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Set user password 

sudo passwd username
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add user passswd

Switch user 

su username
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add new group with own home directory with custom user id and group and custom comment to user geet, with login shell bash 

useradd -m -d /home/geet -u 1029 -g 1822 -c "geet user" -s /bin/bash geet
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Create new group

Create a new group

Linux daddy will guide you

sudo addgroup groupName
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addgroup

You are now daddy

sudo groupadd grp1
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create new group

Create group with custom ID 

sudo groupadd -g 2218 groupName
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Add user to group 

# sudo usermod --append --groups demo user1 sudo usermod -aG groupname userName
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usermod

Display details about group 

sudo cat /etc/gshadow
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Change primary group of geet to ak 

sudo usermod -g ak geet
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Add geet as a menber of group jeet 

sudo gpasswd -M geet jeet
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Remove user geet from group jeet 

sudo gpasswd -d geet jeet
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Make geet admin of group jeet 

sudo gpasswod -A geet jeet
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Set password for group jeet 

sudo gpasswd jeet
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Delete user and group

Delete user 

sudo userdel geet
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Delelet user with all files 

sudo userdel -r geet
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Delete Group 

sudo groupdel jeet
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Top comments (2)

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akshar2001 profile image
Akshar Parmar •

Great!

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scorcism profile image
Abhishek Pathak •

Thank you :)