Hcfyk

I have the following script that SSH to a server with a key and makes a lot of stuff there.

#!/usr/bin/env bash



ssh -i mykey.pem myuser@SERVER_IP << 'ENDSSH'

[A LOT OF STUFF]

ENDSSH

(which I run it with sh scriptname.sh)

Now I want to to the same in another server, so I've to SSH to two different servers (ip_1 and ip_2) with two different .pem files (mykey1.pem and mykey2.pem).

So far I know how to loop the ips as follows:

#!/usr/bin/env bash



ip_list="ip_1 ip_2"



for ip in $ip_list; do

ssh -i mykey.pem myuser@$ip << 'ENDSSH'

[A LOT OF STUFF]

ENDSSH

done

but now I would like to loop also to get the proper pem file. How can I archieve this? Maybe with another list? Can someone provide me an elegant solution?

• 
  ip_1 should use mykey1.pem
  


• 
  ip_2 should use mykey2.pem
  

Thanks in advance

Since you're using bash, you can use associative arrays:

#!/usr/bin/env bash



declare -A ip_list=(["ip_1"]="mykey1.pem" ["ip_2"]="mykey2.pem")



for ip in "${!ip_list[@]}"; do

  ssh -i  "${ip_list[$ip]}" myuser@"$ip" << 'ENDSSH'

[A LOT OF STUFF]

ENDSSH

done

Note that associative arrays, unlike regular indexed arrays, are not saved in a specific order, so there is no guarantee that ip_1 will be processed before ip_2.

If you need to use a simple, POSIX compatible shell, create a file with the ip and key files, one per line:

$ cat iplist.txt

ip1 mykey1.pem

ip2 mykey2.pem

Then, use this script:

#!/bin/sh



while read -r ip key; do

    ssh -i "$key" myuser@"$ip" << 'ENDSSH'

[A LOT OF STUFF]

ENDSSH

done 

And run it with:

sh /path/to/script <  /path/to/iplist.txt

But if you go that route, Stéphane's approach is better.

One way to do it is to use a while IFS=, read -r loop on a csv here-document.

#! /bin/sh -

while IFS=, read <&3 -r ip key; do

  ssh -i "$key" "$ip" << ENDSSH

  ...

ENDSSH

done 3<< ENDCSV

10.0.0.1,p1.pem

10.0.0.2,p2.pem

ENDCSV

Then you don't even need to require users to install bash. If portability is not a concern, you could use zsh instead which supports looping over more than one variable.

#! /usr/bin/env zsh

for ip key (

  10.0.0.1 p1.pem

  10.0.0.2 p2.pem

) ssh -i $key $ip << ENDSSH

  ...

ENDSSH

Your original script can be made slightly more portable via set built-in, plus have ip and key go together as one string, colon separated. We later can use prefix and suffix removal to extract corresponding entry

#!/usr/bin/env bash



# Set positional parameters

# Example ip addresses

set -- 192.168.0.1:mykey1 192.168.1.1:mykey2



# iterating without specifying 'in' assumes positiona parameters

for host; do

    ssh -i ${host##*:}.pem myuser@${host%%:*} << 'ENDSSH'

[A LOT OF STUFF]

ENDSSH



done