How to create user in linux by providing uid and gid options? [closed]

Question

I have 2 linux machines. On one machine these are the users:

sysadmin2:x:4201:4200::/home/sysadmin2:/bin/bash
appadmin1:x:4100:4100::/home/appadmin1:/bin/bash
appadmin2:x:4101:4100::/home/appadmin2:/bin/bash
dataadmin1:x:4300:4300::/home/dataadmin1:/bin/bash
dataadmin2:x:4301:4300::/home/dataadmin2:/bin/bash
sysadmin1:x:4200:4200::/home/sysadmin1:/bin/bash

I want to replicate these to another machine. How can I create these users with same uid and gid values? Is there a way I can copy them to another machine?

Answer 1

First, create the group if it doesn't exist:

$ groupadd -g 4200 sysadmin2

Next, create the user and add it to the group:

$ useradd sysadmin2 -u 4201 -g 4200 -m -s /bin/bash
$ useradd appadmin1 -u 4100 -g 4100 -m -s /bin/bash 

and don't forget to reset password for each user.

Answer 2

In summary and in general, you can use the useradd command to add users to a linux system. The -u flag allows you to set a specific user id and the -g flag allows you to set a specific group id. Please see useradd's manpage for more details -- on a terminal, type man useradd to see it.

Now, specifically about your problem, see below.

Assumming you have three groups on your original machine:

$ cat /etc/group
...
appadmins:x:4100:
sysadmins:x:4200:
dataadmins:x:4300:
...

On your destination/new machine, you should first create the groups using:

groupadd appadmins -g4100
groupadd sysadmins -g4200
groupadd dataadmins -g4300

Then, you can proceed to create the actual users like so:

useradd appadmin1 -u4100 -g4100 -d/home/appadmin1 -s/bin/bash
useradd appadmin2 -u4101 -g4100 -d/home/appadmin1 -s/bin/bash
useradd sysadmin1 -u4200 -g4200 -d/home/sysadmin1 -s/bin/bash
useradd sysadmin2 -u4201 -g4200 -d/home/sysadmin2 -s/bin/bash
useradd dataadmin1 -u4300 -g4300 -d/home/dataadmin1 -s/bin/bash
useradd dataadmin2 -u4301 -g4300 -d/home/dataadmin2 -s/bin/bash

The -d option is used to set the home directory and the -s option is used to set the shell. Again, -u and -g are used to set a specific user and group id.

To check that everything went correctly, just use grep admin on your /etc/passwd file:

$ grep admin /etc/passwd
appadmin1:x:4100:4100::/home/appadmin1:/bin/bash
appadmin2:x:4101:4100::/home/appadmin1:/bin/bash
sysadmin1:x:4200:4200::/home/sysadmin1:/bin/bash
sysadmin2:x:4201:4200::/home/sysadmin2:/bin/bash
dataadmin1:x:4300:4300::/home/dataadmin1:/bin/bash
dataadmin2:x:4301:4300::/home/dataadmin2:/bin/bash

If something is wrong, you can use userdel or groupdel accordingly and start over.