quick way to adduser and userdel in multiple machines

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Problem :

Currently I just go to each of our servers to type

adduser <username> --firstuid 1101 --gid 1001 --disabled-password

to add a user. Is there a quicker way to do so on all servers at the same time? Thanks.


After running the above command, some user information is required to be filled: “Full Name:”,”Room Number”, “Work Phone”, etc. I would like to only fill in this information once and to be used for the user creation on all machines. Thanks.

Solution :


I am not sure if you need to add the same users to each server or if each server has its own user. I will give you a solution for either situation.

Adding a list of users to each server

The best tool for this job is newusers. You will need to create a text file containing the list of users and their details. If you want to add the same user to each server, this file will only need one line.

  1. Create the user’s list. The general format of the file is

    username:passwd:UID:GID:full name,room number,work phone,home phone,other:directory:shell

    So, in your case, you would need to use something like

    tom:password1:::"Tom Hanks","101","123456","654321","Tall"::
    danny:password2:::"Danny DeVito","102","222333","333222","Short"::

    Note that I have left the UID, GUID, directory and shell options empty. This means that default values will be used.

  2. Now that you have created the list, you will need to copy it to each remote machine and then add the new users. For this, you will still need a list of relevant hostnames or IPs, one per line, as in my previous suggestion. Once you have all this set up, save this little script as newusers.sh:

       while read ip; do
         scp users.txt root@$ip:/home/root
         ssh root@$ip newusers users.txt
  3. Make the script executable (chmod a+x newusers.sh) and run it for each IP in your file:

    newusers.sh < IPs.txt
  4. This will all be much easier if you have password-less ssh set up. If you don’t, run the following commands to use ssh keys allowing password-less access (you will still need a passphrase):

    ssh-keygen -t rsa
    while read ip; do ssh-copy-id -i ~/.ssh/id_rsa.pub root@$ip; done < IPs.txt

Adding a different user to each server

In this case, I would create a slightly different file. It should have an IP or hostname, its corresponding user and the details needed to create her on each line. Assuming you want to set up passwords, you can have the plain text (obviously some security concerns here, don’t know if they are relevant in your case) password as the fourth field. Also, in order to correctly parse names with spaces, make sure you use a non-space charcater as field separator. In the example below, I am using - :"Tom Hanks","101","123456","654321","Tall"-pass1"Danny DeVito","102","222333","333222","Short"-pass2

Now loop through the file and create each user on the corresponding machine. Make sure to set the IFS variabe to your field separator in order to parse spaces correctly:

while IFS='-' read ip name opts pass; do 
   ssh root@$ip useradd $name -mc $opts -p `openssl passwd $pass` -s /bin/bash 
done < list.txt

Why not use some centralized user database, like LDAP (either OpenLDAP or better 389 Directory Server)?

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