How to echo variable inside single quotes using Bash?

Question

users.I want to run a curl command with a bash script. (below command works perfectly in terminal)

curl -i -H \"Content-Type: application/json\" -X POST -d \'{\"         


        

Answer 1

I'd probably do it with a printf format. It makes it easier to see formatting errors, and gives you better control over your output:

final="/gua-la-autentica-1426251559"

fmt='{"mountpoint":"%s"}'

curl -i -H "Content-Type: application/json" -X POST \
  -d "$(printf "$fmt" "$final")" \
  http://127.0.0.1:5000/connect

I don't know where you're getting $final in your actual use case, but you might also want to consider checking it for content that would break your JSON. For example:

Portable version:

if expr "$final" : '[A-Za-z0-9./]*$'; then
  curl ...
else
  echo "ERROR"
fi

Bash-only version (perhaps better performance but less portable):

if [[ "$final" ]~ ^[A-Za-z0-9./]*$ ]]; then
  curl ...
...

Checking your input is important if there's even the remote possibility that your $final variable will be something other than what you're expecting. You don't have valid JSON anymore if it somehow includes a double quote.

Salt to taste.