User & Group management : Complete Beginner’s Guide

Last updated on March 12th, 2018 at 07:37 pm

One of the major work of a System Administrator is User & Group Management. We have to create new users & groups, delete old ones, providing users access to a group or folder etc etc. So, in this tutorial, we will learn how we can manage users & groups.

Linux systems have two types of users, general/normal user and root/super user . While general users have limited access to the Linux system, root users have access to anything & everything on the Linux system.

When a user is created a group with the same user name is also created. Every user has its own home directory, for user root its /root & for general users its located in /home/. Records with all the user information for all the users is maintained in /etc/passwd file & records for all the groups are kept /etc/group.

Let’s discuss these files in brief before we discuss the commands for user & group management

(Recommended Read: Learn how to use tcpdump command with examples)



This file contains list of all users with every line of the file containing information regarding single user. Format for each line is

Username:x:UID:GID:Comment:Home Directory: Default shell

Here, x is password for the user in encrypted form (stored in /etc/shadow file)

UID, is the user id

& GID is the group id for the user.



Just like /etc/passwd, it contains information for groups with each line having information for single group. Format for entries in this file is

Group name:x:GID:members

user management

Where, x again means password in encrypted format.

Now let’s discuss commands for user & group management.


USER Management

Below mentioned are the commands that are used for user management,

Purpose                                                                                  Command

  • Adding a user                                                                 useradd dan
  • Assigning password to user                                    passwd dan
  • Changing home directory for user                      useradd dan –d /home/new
  • Setting expiry for user                                               useradd dan –e 2017-11-25
  • Addding inactive period before expiry              useradd dan –f 2
  • Changing default shell                                              useradd dan –s /bin/sh
  • Removing user                                                            userdel dan
  • Removing user with home directory                 userdel –r dan

We can also modify default settings of a user after it has bee added with usermod command

  • Setting expiry for user                                            usermod –e 2017-11-25 dan
  • Changing home directory                                      usermod –d /home/new dan
  • Changing default shell                                            usermod –s /bin/sh dan
  • Locking an account                                                     usermod –L dan
  • Unlocking a locked account                                    usermod –u dan


Group Management

Following are the commands for managing groups

  • Adding a group                                                             groupadd  linuxgroup
  • Adding user to group                                                 usermod –aG linuxgroup dan
  • Changing owner & group of a file                        chown dan:linuxgroup newfile.txt
  • Changing only owner of a file                              chown dan: newfile.txt
  • Changing only group of a file                               chown :linuxgroup newfile.txt
  • Deleting a group                                                           groupdel linuxgroup


This completes our tutorial on user & group management. We will also discuss File permissions & permission management in our future tutorial.

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1 Response

  1. January 15, 2018

    […] User & Group management : Complete Beginner’s Guide […]

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