Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Mastering User Management on Linux
Are you working as Linux admin? Do you create/delete users in Linux Command line? If yes, then this article is for you guys! After reading the below content, you will be able to manipulate users and group permissions in Linux system.
In the below example sai is the username.
usermod
The usermod command modifies the approach account records to reflect the alterations which can be targeted on the command line.
To get more information about usermod, use the following command –
$ usermod --help
The sample output should be like this –
-c, --comment COMMENT new value of the GECOS field -d, --home HOME_DIR new home directory for the user account -e, --expiredate EXPIRE_DATE set account expiration date to EXPIRE_DATE -f, --inactive INACTIVE set password inactive after expiration to INACTIVE -g, --gid GROUP force use GROUP as new primary group -G, --groups GROUPS new list of supplementary GROUPS -a, --append append the user to the supplemental GROUPS mentioned by the -G option without removing him/her from other groups .....................................................................
Usage of usermod
The usage of usermod should be like this –
$sudo usermod [options] [user Name]
Home directory for New user
To create a new home directory for the user account, use the following command –
$ sudo usermod --home /home sai
Account expiration date
To set account expiration date to EXPIRE_DATE, use the following command –
$ sudo usermod --expiredate 20017-2-24 sai
Lock the user account
To lock the user account, use the following command –
$ sudo usermod --lock sai
Unlock the user account
To unlock the user account, use the following command –
$ sudo usermod --unlock sai
Password for The user
To set the password for the user, use the following command –
$ sudo usermod --password 123456 sai
Adding the user to group
To add the user to group, use the following command –
$ sudo usermod --append --groups root,users sai
Useradd
Useradd is a low degree utility for adding users. On Debian, Admins normally use adduser to create the users on Linux system.
To get more information about user add, use the following command –
$ sudo useradd --help
The sample output should be like this –
-b, --base-dir BASE_DIR base directory for the home directory of the new account -c, --comment COMMENT GECOS field of the new account -d, --home-dir HOME_DIR home directory of the new account -D, --defaults print or change default useradd configuration -e, --expiredate EXPIRE_DATE expiration date of the new account -f, --inactive INACTIVE password inactivity period of the new account -g, --gid GROUP name or ID of the primary group of the new account .....................................................................................
Usage of useradd
The usage of useradd, should be like as shown below –
$ sudo useradd [options] [user name]
Base directory for new account
To create base directory for new account, use the following command –
$ sudo useradd --base-dir /tmp sai
Home directory for new account
To create home directory of the new account, use the following command –
$ sudo useradd --home-dir /home sai
Account expiration date
To set account expiration date to EXPIRE_DATE, use the following command –
$ sudo useradd --expiredate 20017-2-24 sai
Password for the user
To set the password for the user, use the following command –
$ sudo useradd --password 123456 sai
Adding the user to group
To add the user to group, use the following command –
$ sudo usermod --append --groups root,users sai
userdel
Userdel is a low-level utility for disposing of users On Debian, Linux admins most of the time use deluser to delete a consumer on Linux.
To get the more information about userdel, use the following command –
$ userdel --help
The sample output should be like this –
-f, --force force removal of files, even if not owned by user -h, --help display this help message and exit -r, --remove remove home directory and mail spool -R, --root CHROOT_DIR directory to chroot into -Z, --selinux-user remove any SELinux user mapping for the user
Usage of userdel
The usage of userdel should be like this –
$sudo userdel [options] [user name]
Delete the user
To delete the user, use the following command –
$ sudo userdel sai
Deleting the user with files
To delete the user with files, use the following command –
$ sudo userdel --force sai
Remove the user of home directory
To remove the user of home directory, use the following command
$ sudo userdel --remove sai
Changing password expiration time
To change the time the user’s password will expire, use the following command as shown below –
$ sudo chage sai
The sample output should be like this –
Changing the aging information for sai Enter the new value, or press ENTER for the default Minimum Password Age [0]: 20 Maximum Password Age [99999]: 20 Last Password Change (YYYY-MM-DD) [2017-02-01]: Password Expiration Warning [7]: 7 Password Inactive [-1]: -1 Account Expiration Date (YYYY-MM-DD) [-1]: 2017-02-28
Changing User full name information
To change the user full name field finger information, use the following command as shown below –
$ sudo chfn sai
The sample output should be like this –
Changing the user information for sai Enter the new value, or press ENTER for the default Full Name [sai]: sairamkrishna mammahe Room Number []: Work Phone []: Home Phone []: Other []:
Changing the owner files to another user
To change the owner of file(s ) to another user.In the below command, we are changing owner file of home directory to sai(user) as shown below –
$ sudo chown sai /home
Examine Faillog
To examine faillog, use the following command as shown below –
$ sudo faillog -a
The sample output should be like this –
Login Failures Maximum Latest On root 0 0 01/01/70 05:30:00 +0530 daemon 0 0 01/01/70 05:30:00 +0530 bin 0 0 01/01/70 05:30:00 +0530 sys 0 0 01/01/70 05:30:00 +0530 sync 0 0 01/01/70 05:30:00 +0530 games 0 0 01/01/70 05:30:00 +0530 man 0 0 01/01/70 05:30:00 +0530 lp 0 0 01/01/70 05:30:00 +0530 mail 0 0 01/01/70 05:30:00 +0530 news 0 0 01/01/70 05:30:00 +0530 uucp 0 0 01/01/70 05:30:00 +0530 .......................................................................
Create a new Group
To create a new group, use the following command as shown below –
$ sudo groupadd sai
In the above command sai is the group name.
Verifying the integrity of groupd files
To verify the integrity of group files. use the following command as shown below –
$ sudo grpck
Deleting a group
To delete a group, use the following command as shown below –
$ sudo groupdel sai
Printing the groups
To print the groups a user is in, use the following command as shown below –
$ sudo groups
The sample output should be like this –
root
Printing user ids and group ids
To print real and effective user id and group ids, use the following command as shown below –
$ sudo id
The sample output should be like this –
uid=0(root) gid=0(root) groups=0(root)
Last user logged information
To display the last users logged on and how long, use the following command as shown below –
$ sudo last
The sample output should be like this –
linux tty7 :0 Wed Feb 1 09:49 gone - no logout reboot system boot 4.4.0-59-generic Wed Feb 1 09:48 still running guest-er tty8 :1 Mon Jan 30 15:47 - down (00:00) linux tty7 :0 Fri Jan 27 09:33 - down (3+06:15) reboot system boot 4.4.0-59-generic Fri Jan 27 09:32 - 15:48 (3+06:16) linux tty7 :0 Mon Jan 23 09:10 - down (2+08:51) reboot system boot 4.4.0-59-generic Mon Jan 23 09:09 - 18:01 (2+08:52) linux tty7 :0 Fri Jan 20 09:17 - crash (2+23:51) reboot system boot 4.4.0-59-generic Fri Jan 20 09:17 - 18:01 (5+08:44) linux tty7 :0 Wed Jan 18 14:21 - down (03:38) ...........................................................................
Failed login attempts information
To should the failed login attempts, use the following command as shown below –
$ sudo lastb
The sample output should be like this –
linux tty8 :1 Wed Jan 25 11:16 - 11:16 (00:00) sai tty8 :1 Wed Jan 25 11:15 - 11:15 (00:00) sai Wed Jan 25 11:15 - 11:15 (00:00) linux tty8 :1 Wed Jan 25 11:15 - 11:15 (00:00) sai tty8 :1 Wed Jan 25 11:15 - 11:15 (00:00) sai tty8 :1 Wed Jan 25 11:15 - 11:15 (00:00) sai Wed Jan 25 11:14 - 11:14 (00:00) linux tty7 :0 Mon Jan 9 11:04 - 11:04 (00:00) btmp begins Mon Jan 9 11:04:59 2017
Login with root
To login with root, use the following command as shown below –
$ sudo sulogin
The sample output should be like this –
Give root password for maintenance (or press Control-D to continue):
Logged information and usage
To display users logged in and what they are doing, use the following command as shown below –
$ sudo w
The sample output should be like this –
11:45:38 up 1:57, 1 user, load average: 0.10, 0.39, 0.37 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT linux tty7 :0 09:49 1:57m 3:22 0.28s /sbin/upstart -
User information
To display the users logged in, use the following command as shown below –
$sudo who
The sample output should be like this –
linux tty7 2017-02-01 09:49 (:0)
User id information
To display the user id infromation, use the following command as shown below –
$sudo whoami
The sample output should be like this –
root
In this article, we have learnt about – Mastering user management on Linux, we will come up with more Linux based tricks and tips. Keep reading!
154 Views
