how to re-run the "curl" command automatically when the error occurs

Question

Sometimes when I execute a bash script with the curl command to upload some files to my ftp server, it will return some error like:

56 response reading failed

and I have to find the wrong line and re-run them manually and it will be OK.

I'm wondering if that could be re-run automatically when the error occurs.

---

My scripts is like this:

#there are some files(A,B,C,D,E) in my to_upload directory,
# which I'm trying to upload to my ftp server with curl command
for files in `ls` ;
    do curl -T $files ftp.myserver.com --user ID:pw ;
done

But sometimes A,B,C, would be uploaded successfully, only D were left with an "error 56", so I have to rerun curl command manually. Besides, as Will Bickford said, I prefer that no confirmation will be required, because I'm always asleep at the time the script is running. :)

Answer 1

Here's a bash snippet I use to perform exponential back-off:

# Retries a command a configurable number of times with backoff.
#
# The retry count is given by ATTEMPTS (default 5), the initial backoff
# timeout is given by TIMEOUT in seconds (default 1.)
#
# Successive backoffs double the timeout.
function with_backoff {
  local max_attempts=${ATTEMPTS-5}
  local timeout=${TIMEOUT-1}
  local attempt=1
  local exitCode=0

  while (( $attempt < $max_attempts ))
  do
    if "$@"
    then
      return 0
    else
      exitCode=$?
    fi

    echo "Failure! Retrying in $timeout.." 1>&2
    sleep $timeout
    attempt=$(( attempt + 1 ))
    timeout=$(( timeout * 2 ))
  done

  if [[ $exitCode != 0 ]]
  then
    echo "You've failed me for the last time! ($@)" 1>&2
  fi

  return $exitCode
}

Then use it in conjunction with any command that properly sets a failing exit code:

with_backoff curl 'http://monkeyfeathers.example.com/'

Answer 2

Perhaps this will help. It will try the command, and if it fails, it will tell you and pause, giving you a chance to fix run-my-script.

COMMAND=./run-my-script.sh 
until $COMMAND; do 
    read -p "command failed, fix and hit enter to try again."
done