2

Ok, there are similar questions, but not exactly what I am looking for.

I am working with Kubernetes, so the information is from that, but this question is for Shell Scripting, so please don't push me off to Kubernetes people. :)

I run the following command to get the information:

kubectl get pods -o wide --all-namespaces | grep sonarqube-

Result Example:

default       sonarqube-664b4fd48-g6nvb                   1/1       Running   0          4d        10.233.64.6     local-node-0

Goal: What I want is to take the first 2 values (default and sonarqube-664b4fd48-g6nvb) and turn them into variables that I can use elsewhere in the script.

Command Sample I want to use the variables in is like:

kubectl cp <file> ${namespace}/${deployment}:/opt/app/extensions/plugins/

Thanks, and please let me know if more information is needed.

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2

generally

What will work in bash and in other shells is to set positional parameters from the output of the pipe:

set -f -- $(kubectl get pods -o wide --all-namespaces | grep sonarqube- )

In this case, you can now access the variables as $1, $2, etc.

specifc for bash

In bash it is possible to create an array variable, like so:

var=( $(kubectl get pods -o wide --all-namespaces | grep sonarqube- ) )

The idiom is var=( ... ), in this case the output of your grep pipe.

You can then access elements of your array using the form ${var[n]}, with n starting at zero.

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  • This worked perfectly! Thanks! (tried to up-vote, but need more street cred I guess). – DC.Skells Mar 6 '18 at 21:46
  • @DennisChristilaw That's ok. The expected thing to do is to mark the answer accepted with the check mark. – user1404316 Mar 6 '18 at 21:49
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    As long as the first two words in the output don't contain wildcards... Something like * as the first output word would fill the positional parameters with the filenames in the current directory, which is not what you want. Use set -f first if that's a risk. – ilkkachu Mar 6 '18 at 21:57
  • @ilkkachu - Quite right, The OP is explicitly and specifically asking about parsing the output of kubectl, but your comment is proper for me to amend my answer, thanks. – user1404316 Mar 6 '18 at 22:08
  • @user1404316 Even though the output was from kubectl, this question/answer helped in other applications too. Thanks to the answer and help, I now have something I can use for more than just kubectl output. :) – DC.Skells Mar 6 '18 at 22:37
3

With bash's read function:

read -r namespace deployment other < <(kubectl get pods -o wide --all-namespaces | grep sonarqube-)
kubectl cp <file> "${namespace}/${deployment}:/opt/app/extensions/plugins/"
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  • Very good. This approach nicely avoids the common bash traps of unexpected word splitting and pathname expansion. – John1024 Mar 6 '18 at 21:46
0

In cases like this (with predictable output columns), I usually reach for awk. Something like this might be useful:

kubectl get pods -o wide --all-namespaces | awk '/sonarqube-/ { cmd=sprintf("kubectl cp <file> %s/%s:/opt/app/extensions/plugins", $1, $2); print(cmd); system(cmd); }'
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