Add User, Group, File to check users & groups

Add user account on Ubuntu

useradd <username>

The following command line will create the user named testuser and give them their own home directory in /home/testuser. The files in the new home directory are copied from the /etc/skel folder, which contains default home directory files. If you wanted to set default values for your users, you would do so by modifying or adding files in that directory.

sudo useradd -d /home/testuser -m testuser

sudo passwd testuser

If we take a look at the new home directory for the

user:geek@ubuntuServ:/etc/skel$ ls -la /home/testuser

total 20
drwxr-xr-x 2 testuser testuser 4096 2006-12-15 11:34 .
drwxr-xr-x 5 root root 4096 2006-12-15 11:37 ..
-rw-r–r– 1 testuser testuser 220 2006-12-15 11:34 .bash_logout
-rw-r–r– 1 testuser testuser 414 2006-12-15 11:34 .bash_profile
-rw-r–r– 1 testuser testuser 2227 2006-12-15 11:34 .bashrc

You’ll notice that there are bash scripts in this directory. If you wanted to set default path options for all new users, you would do so by modifying the files in /etc/skel, which would then be used to create these files by the useradd command.

Setup password for user

# passwd <username>

Add group

groupadd <groupname>

Add user to group

useradd -G <groupname> <username>

Ensure user added properly to group developers

# id

output

uid=1122(vivek) gid=1125(vivek) groups=1125(vivek),1124(developers)

Please note that capital G (-G) option add user to a list of supplementary groups. Each group is separated from the next by a comma, with no intervening whitespace. For example, add user jerry to groups admins, ftp, www, and developers, enter:
# useradd -G admins,ftp,www,developers jerry

useradd example – Add a new user to primary group

To add a user tony to group developers use following command:
# useradd -g developers tony
# id tony

Sample outputs:

uid=1123(tony) gid=1124(developers) groups=1124(developers)

Please note that small -g option add user to initial login group (primary group). The group name must exist. A group number must refer to an already existing group.

usermod example – Add a existing user to existing group

Add existing user tony to ftp supplementary/secondary group with usermod command using -a option ~ i.e. add the user to the supplemental group(s). Use only with -G option :
# usermod -a -G ftp tony
Change existing user tony primary group to www:
# usermod -g www tony

Remove a user from a group

deluser <username> <groupname>

Remove a user account

# userdel <username>

# userdel -r <username>

-r option will remove the user’s home directory as well.

File to check users and groups:

/etc/passwd

/etc/group

use command to see users and user information

# cat /etc/passwd (vi /ect/passwd)

or

# lastlog

Add a User

  • add user on Linux Server: take nina as a example
  • add nina to www group password: ninatang
  • useradd -g www nina
  • vi ninapas
  • nina:ninatang
  • chpasswd < ninapas
  • change group the user belong to: usermod -g newgroup nina

See Which Groups Your Linux User Belongs To

When you are using a linux system, it’s useful to find out what groups you belong to, so you can understand whether you have access to files and directories. This is one of the simplest commands possible. I’m using Ubuntu linux, but this command should work on most varieties of linux.

groups <username>

If you don’t enter a username, it defaults to your own username. For instance:

geek@ubuntuServ:$ groups
geek adm dialout cdrom floppy audio dip video plugdev lpadmin scanner admin fuse

You can also check the groups for any other user, including root:

geek@ubuntuServ:$ groups root
root : root fuse

I used this command recently to make sure that my user account was part of the “fuse” group, when I was getting sshfs set up. Very useful.

http://www.howtogeek.com/howto/ubuntu/see-which-groups-your-linux-user-belongs-to/

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About zephyr9000

Happy sailer
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