This may be a bit late to the show for this thread.. But this is fairly streight forward. My pssh commands are a bit rusty but here are my notes:
#########
How to create a set of lists and then when you want to run a command on all nodes in that group (array) then run them in parallel on cluster nodes
Documentation:
https://www.tecmint.com/execute-commands-on-multiple-linux-servers-using-pssh/
Step 1: Installation
yum install python-pip
pip install --upgrade pip
pip install pssh
Step 2: Create cluster file
vi /root/clusternodes
thor.test.local
odin.test.local
kmstr01.test.local
kmstr02.test.local
kmstr03.test.local
kproxy01.test.local
kproxy02.test.local
kproxy03.test.local
kworker01.test.local
kworker02.test.local
Step 3: Run parallel command
[root@kmstr01 ~]# pssh -h clusternodes 'uname -a'
[1] 09:06:43 [SUCCESS] thor.test.local
[2] 09:06:43 [SUCCESS] odin.test.local
[3] 09:06:43 [SUCCESS] kmstr01.test.local
[4] 09:06:43 [SUCCESS] kworker01.test.local
[5] 09:06:43 [SUCCESS] kmstr02.test.local
[6] 09:06:43 [SUCCESS] kproxy01.test.local
[7] 09:06:43 [SUCCESS] kproxy03.test.local
[8] 09:06:43 [SUCCESS] kworker02.test.local
[9] 09:06:43 [SUCCESS] kproxy02.test.local
[10] 09:06:43 [SUCCESS] kmstr03.test.local
Your command would be : Ex: remove 'bob' from wheel gpasswd -d user group
pssh -h clusternodes 'gpasswd -d bob wheel'