Bash retry function with exponential backoff

retry.sh

#!/bin/bash

# Retry a command with exponential backoff
function retry {
  local maxAttempts=$1
  local secondsDelay=1
  local attemptCount=1
  local output=
  shift 1

  while [ $attemptCount -le $maxAttempts ]; do
    output=$("$@")
    local status=$?

    if [ $status -eq 0 ]; then
      break
    fi

    if [ $attemptCount -lt $maxAttempts ]; then
      echo "Command [$@] failed after attempt $attemptCount of $maxAttempts. Retrying in $secondsDelay second(s)." >&2
      sleep $secondsDelay
    elif [ $attemptCount -eq $maxAttempts ]; then
      echo "Command [$@] failed after $attemptCount attempt(s)" >&2
      return $status;
    fi
    attemptCount=$(( $attemptCount + 1 ))
    secondsDelay=$(( $secondsDelay * 2 ))
  done

  echo $output
}

retry 1 myfunc

Here is what I invented lol

for i in $(seq 4); do
    ! might-fail-or-not || break
    test "${i}" != "4" || { echo "Reached max attempts"; false; }
    sleep "${i}s"
done