bash - executing ssh command in a loop

Question

I have the loop:

IFS=','
for host in host1,host2
  do 
     ssh root@$host script.sh 
  done

When I execute the loop, ssh command works fine for host1, but for host2 I see:

bash: host2: command not found

Could you tell me where can be the problem?

Splitting on IFS isn't doing what you think it is. Splitting happens on variable expansion, so it doesn't expand the literal value in the for statement, but it does split the when the $host variable is expanded; essentially, it runs ssh root@host1 host2 script.sh. This tries to run host2 as a command on host1. Moral: splitting with IFS is hard to understand and you're generally better off using other methods to get things done (like arrays). — Gordon Davisson
– Gordon Davisson, Commented Jul 23, 2020 at 9:56
I suggest to use an array instead of splitting with a , delimiter. — Jetchisel
– Jetchisel, Commented Jul 23, 2020 at 9:57

Ivan · Accepted Answer · 2020-07-23 10:04:41Z

1

Just like this

for host in host1 host2
  do 
     ssh root@$host script.sh
  done

answered Jul 23, 2020 at 10:04

Ivan

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Comments

coder here · Accepted Answer · 2020-07-23 09:59:19Z

0

You above script will return an output command like this

ssh root@host1 host2 script.sh

Here host2 is considered as an argument or a command which the shell is not able to recognize and hence you are getting the above error.

Assuming your use case is to run the shell script on both hosts the following script might help you

IFS=', ' read -r -a array <<< host1,host2
for host in ${array[@]};   do      ssh root@$host script.sh; done

output command will be similar to below

ssh root@host1 script.sh
ssh root@host2 script.sh

answered Jul 23, 2020 at 9:59

coder here

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wuseman · Accepted Answer · 2020-07-23 11:16:49Z

0

pssh -h hostfile.txt -l root -i "echo 'hello world'; another_command; exit"

answered Jul 23, 2020 at 11:16

wuseman

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