How to upde userid to uid=0 using command line?

Question

Hi all,
I made a new user "sysadmin" by typing at root command line:
# useradd sysadmin (all default profile values)
What is the command (line) to update its UID to "0"?
Thanks you very much in advance.
Ms KK

Answer 1

In general, having multiple accounts with the same UID is a bad idea. To have
multiple "root" accounts is very, very bad idea.
If you need an ordinary mortal user to be able to execute privileged commands,
set up the sudo(1) facility. This will let you grant permission with a fine
level of control about exactly which program or command is being used. As a
bonus, you will get an audit trail of who did what as whom.
The great thing about sudo(1) is that you can grant root privilege without
having to give out root's password.
Now, assume you make duplicate "root" accounts. You get offered a better job
and leave. The new sysadmin will need careful briefing before doing anything.
This will create a major maintainability issue long term.
If you want another root user for disaster recovery or losing the password,
there are better alternatives such as:
-- Reboot the system using rescue mode from the installation disks.
-- Boot into single-user mode by interrupting the GRUB install sequence and appending "s" to the kernel command line.
-- Boot into an interactive shell by appending the "init=/bin/bash" clause using the same technique.
These are some of the known, common, best practice methods of handling this
situation. A custom solution here could be quite dangerous and hard to maintain
in the long run.
Please don't.