Bash: Retry command N times

retry.sh

#!/bin/bash

function retry {
  local n=0
  local max="$1"; shift
  local cmd="$*"

  until $cmd; do
    if [ "$((++n))" -lt "$max" ]; then
      echo "Retrying in $((n*2)) seconds..."
      sleep "$((n*2))"
    else
      echo "Failed after $n attempts: $cmd"
      return 1
    fi
  done
}

retry 3 ping foobar