Retry a command with exponential backoff

Thu, 14 May 2026 00:00:00 +0000

Network calls fail for a second and then work fine. A script shouldn’t die over that. This wraps any command, retrying with a doubling delay.

# retry — run a command up to N times with exponential backoff.
# Usage: retry 5 curl -sf https://example.com
retry() {
 local max="$1"; shift
 local n=1 delay=1
 until "$@"; do
 if (( n >= max )); then
 echo "retry: '$*' failed after $max attempts" >&2
 return 1
 fi
 echo "retry: attempt $n failed; sleeping ${delay}s" >&2
 sleep "$delay"
 (( n++, delay *= 2 ))
 done
}

It returns the command’s success once it passes, or 1 after exhausting the attempts — so it drops straight into a set -e script:

Reliability on buildx.sh

Retry a command with exponential backoff