curl returns empty reply from server bash due to curl failure

Question

i am writing a simple bash script to "curl get" some values. Sometimes the code works and sometimes it fails, and says "empty reply from server". How to set up a check for this in bash so that if the curl fails once it tries again until it gets the values?

Answer 1

while ! curl ...    # add your specific curl statement here
do
    { echo "Exit status of curl: $?"
      echo "Retrying ..."
    } 1>&2
    # you may add a "sleep 10" or similar here to retry only after ten seconds
done

In case you want the output of that curl in a variable, feel free to capture it:

output=$(
  while ! curl ...    # add your specific curl statement here
  do
      { echo "Exit status of curl: $?"
        echo "Retrying ..."
      } 1>&2
      # you may add a "sleep 10" or similar here to retry only after ten seconds
  done
)

The messages about the retry are printed to stderr, so they won't mess up the curl output.

Answer 2

People are overcomplicating this:

until contents=$(curl "$url")
do
  sleep 10
done

Answer 3

For me sometimes it happens when curl timed out and there is no information about that. Try curl with --connect-timeout 600 (in seconds) like:

  curl --connect-timeout 600 "https://api.morph.io/some_stuff/data.json"

Maybe this helps you.

Answer 4

if you wanted to try the command until it succeeded, you could say:

command_to_execute; until (( $? == 0 )); do command_to_execute; done