Bash retry helper to retry a command N times with delay and optional exponential backoff (strict-mode friendly).

bash-retry.sh

#!/usr/bin/env bash
# -----------------------------------------------------------------------------
# Bash retry helper
# -----------------------------------------------------------------------------
# Usage:
#   retry <attempts> <delay_seconds> <command...>
#
# Example:
#   retry 5 2 curl -f https://example.com
#
# Optional:
#   Set RETRY_BACKOFF=1 to enable exponential backoff.
# -----------------------------------------------------------------------------

set -Eeuo pipefail

retry() {
  local attempts="$1"
  local delay="$2"
  shift 2

  local count=1
  local exit_code=0

  if [[ -z "${attempts:-}" || -z "${delay:-}" || $# -eq 0 ]]; then
    echo "Usage: retry <attempts> <delay_seconds> <command...>" >&2
    return 2
  fi

  while (( count <= attempts )); do
    echo "Attempt $count/$attempts: $*"

    if "$@"; then
      return 0
    fi

    exit_code=$?

    if (( count == attempts )); then
      echo "Command failed after $attempts attempts." >&2
      return "$exit_code"
    fi

    echo "Command failed with exit code $exit_code. Retrying in ${delay}s..." >&2
    sleep "$delay"

    if [[ "${RETRY_BACKOFF:-0}" -eq 1 ]]; then
      delay=$(( delay * 2 ))
    fi

    ((count++))
  done
}

# ---------------------------------------------------------------------------
# Example usage (uncomment to test)
# ---------------------------------------------------------------------------

# retry 5 1 ls /nonexistent
# RETRY_BACKOFF=1 retry 5 1 curl -f https://example.com