Bash: Pass variable to other server in shell script

Question

I have controller node (CN) and server nodes (SN). From CN, I need to config the hostname of each and every SN. inv file contains list of SNs and corresponding hostname.

In below script, I am not sure how to pass hostname variable. Any best way to achieve same?

#!/bin/bash

IFS='\n'

for data in `awk 'NR>1 {print}' inv`
do
        ip=`awk '{print $1}' <<< $data`
        hostname=`awk '{print $2}' <<< $data`
        ssh root@$ip "hostnamectl set-hostname $hostname"
done

inv file,

IPs                     Hostname
172.31.98.11            Server1
172.31.106.177          Server2
172.31.97.105           Server3

What exactly do you mean? hostnamectl on the server should already be called with the correct value (the variable is expanded before the string is sent the server. Does the variable contain the correct value? — knittl
– knittl, Commented Apr 25, 2021 at 7:35
@dahiya_boy I still don't understand. Why (and where) do you need the variable on the other server? You only execute a single command and it has the variable's value already expanded. — knittl
– knittl, Commented Apr 25, 2021 at 8:10

anubhava · Accepted Answer · 2021-04-25 07:45:34Z

1

There is no need to use awk here since you are just printing all rows after 1st record. A tail does that job.

You may use this bash script:

while read -r ip hn; do
   ssh root@"$ip" "hostnamectl set-hostname $hn"
done < <(tail -n +2 inv)

answered Apr 25, 2021 at 7:45

anubhava

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2 Comments

200_OK Over a year ago

can you pls explain done < <(tail -n +2 inv) I unable to understand why < < and space b/w them.

anubhava Over a year ago

< <(...) is called process substitution. Read more about it

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