downloading node binary script.sh

#!/bin/bash
set -euo pipefail

# Downloads a node tarball from https://nodejs.org/dist/ and extracts just
# the binary into the current directory. Chiefly we use this to get a node
# binary for uploading to manifold.

if [[ $# -ne 4 ]]; then
  echo "USAGE: $0 <node_version> <os> <arch> <filename>"
  exit 1
fi

node_version=$1
os=$2
arch=$3
node_base="node-v$node_version-$os-$arch"
out=$4

if [ "$os" == "win" ]; then
  url=https://nodejs.org/dist/v$node_version/win-$arch/node.exe
  curl -fSsLo "$out" "$url"
else
  cd "$(mktemp -d)"
  url=https://nodejs.org/dist/v$node_version/$node_base.tar.xz
  curl -fSsL "$url" | tar -xJ
  mv "$node_base/bin/node" "$out"
fi