Wednesday, 9 June 2021

Bash and fun with escape characters

Whilst writing the world's simplest Bash script to: -

  • delete a pod
  • deploy a new pod
  • list the running pods
  • describe the newly deployed pod

I wanted to add newline characters into my echo statements, to make things more readable.

I've written before about echo -e so was just double-checking my understanding via the command-line ...

I entered: -

echo -e "Hello World!\n"

but, instead of a friendly greeting, I saw: -

-bash: !\n: event not found

Wait, what now ?

Yeah, of course, I've entered a magical place escape sequence of: -

pling slash n

which, obviously, isn't what I meant to do ....

Easy solution - stick in a space character ...

echo -e "Hello World! \n"

Hello World! 

So here's the finished script: -



echo -e "Deleting existing busybox-kata pod\n"

kubectl delete pod busybox-kata

echo -e "\nDeploying new busybox-kata pod\n"

kubectl apply -f busybox-kata.yaml 

echo -e "\nSleeping ...\n"

sleep 10

echo -e "\nChecking pods ...\n"

kubectl get pods

echo -e "\nSleeping ...\n"

sleep 5

echo -e "\nDescribing busybox-kata pod to see all is good ...\n"

kubectl describe pod busybox-kata | tail -8

No comments:

Yay, VMware Fusion and macOS Big Sur - no longer "NAT good friends" - forgive the double negative and the terrible pun ...

After macOS 11 Big Sur was released in 2020, VMware updated their Fusion product to v12 and, sadly, managed to break Network Address Trans...