diff --git a/tool b/tool
new file mode 100755
index 0000000..231cd4c
--- /dev/null
+++ b/tool
@@ -0,0 +1,181 @@
+#!/usr/bin/env bash
+set -eu -o pipefail
+
+os=
+case $(uname -s | awk '{print tolower($0)}') in
+  linux*) os=linux;;
+  darwin*) os=mac;;
+  cygwin*) os=cygwin;;
+  *bsd*) os=bsd;;
+  *) os=unknown;;
+esac
+
+
+print_usage() {
+cat <<EOF
+Usage: tool [options] <command> [<args>]
+Options:
+    -v        Print important commands as they're executed.
+    -c <name> Use a specific compiler binary instead.
+              Default: \$CC, or cc
+    -h        Print this message and exit.
+EOF
+}
+
+compiler_exe="${CC:-cc}"
+
+verbose=0
+
+while getopts c:hv- opt_val; do
+  case "$opt_val" in
+    c) compiler_exe="$OPTARG";;
+    v) verbose=1;;
+    h) print_usage; exit 0;;
+    \?) print_usage >&2; exit 1;;
+    *) break;;
+  esac
+done
+
+warn() {
+  echo "Warning: $*" >&2
+}
+fatal() {
+  echo "Error: $*" >&2
+  exit 1
+}
+script_error() {
+  echo "Script error: $*" >&2
+  exit 1
+}
+
+verbose_echo() {
+  if [[ $verbose = 1 ]]; then
+    echo "$@"
+  fi
+  "$@"
+}
+
+if [[ ($os == bsd) || ($os == unknown) ]]; then
+  warn "Build script not tested on this platform"
+fi
+
+# This is not perfect by any means
+cc_id=
+compiler_vers=
+if ${compiler_exe} --version | grep -q ^clang 2> /dev/null; then
+  cc_id=clang
+  compiler_vers=$(${compiler_exe} -dumpversion)
+# Only gcc has -dumpfullversion
+elif compiler_vers=$(${compiler_exe} -dumpfullversion 2> /dev/null); then
+  cc_id=gcc
+fi
+
+if [[ -z $cc_id ]]; then
+  warn "Failed to detect compiler type"
+fi
+if [[ -z $compiler_vers ]]; then
+  warn "Failed to detect compiler version"
+fi
+
+add() {
+  if [[ -z "${1:-}" ]]; then
+    script_error "At least one argument required for array add"
+  fi
+  local array_name
+  array_name=${1}
+  shift
+  eval "$array_name+=($(printf "'%s' " "$@"))"
+}
+
+try_make_dir() {
+  if ! [[ -e "$1" ]]; then
+    verbose_echo mkdir "$1"
+  elif ! [[ -d "$1" ]]; then
+    fatal "File $1 already exists but is not a directory"
+  fi
+}
+
+out_exe=orca
+build_dir=build
+source_files=()
+add source_files field.c mark.c bank.c sim.c
+
+# safety flags:  -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fpie -Wl,-pie
+  #local tui_flags=()
+  #add tui_flags -D_XOPEN_SOURCE_EXTENDED=1
+
+build_target() {
+  local build_subdir
+  local compiler_flags=()
+  local libraries=()
+  add compiler_flags -std=c99 -pipe -Wall -Wpedantic -Wextra -Wconversion -Werror=implicit-function-declaration -Werror=implicit-int -Werror=incompatible-pointer-types -Werror=int-conversion
+  case "$1" in
+    debug)
+      build_subdir=debug
+      add compiler_flags -DDEBUG -ggdb -fsanitize=address -fsanitize=undefined
+      if [[ $os = mac ]]; then
+        # mac clang does not have -Og
+        add compiler_flags -O1
+        # tui in the future
+        # add libraries -lncurses
+      else
+        add compiler_flags -Og -feliminate-unused-debug-symbols
+        # needed if address is already specified? doesn't work on mac clang, at
+        # least
+        # add compiler_flags -fsanitize=leak
+        # add libraries -lncursesw
+      fi
+      ;;
+    release)
+      build_subdir=release
+      add compiler_flags -DNDEBUG -O2 -g0
+      if [[ $os = mac ]]; then
+        # todo some stripping option
+        true
+      else
+        # -flto is good on both clang and gcc on Linux
+        add compiler_flags -flto -s
+      fi
+      ;;
+    *) fatal "Unknown build target \"$1\"";;
+  esac
+  add source_files cli_main.c
+  try_make_dir "$build_dir"
+  try_make_dir "$build_dir/$build_subdir"
+  verbose_echo "${compiler_exe}" "${compiler_flags[@]}" -o "$build_dir/$build_subdir/$out_exe" "${source_files[@]}" "${libraries[@]}"
+}
+
+shift $((OPTIND - 1))
+
+if [[ -z "${1:-}" ]]; then
+  echo "Error: Command required" >&2
+  print_usage >&2
+  exit 1
+fi
+
+case "$1" in
+  info)
+    echo "OS:               $os"
+    echo "Compiler name:    $compiler_exe"
+    echo "Compiler type:    $cc_id"
+    echo "Compiler version: $compiler_vers"
+    exit 0
+    ;;
+  build)
+    if [[ "$#" -gt 2 ]]; then
+      fatal "Too many arguments for 'build'"
+    fi
+    if [ "$#" -lt 1 ]; then
+      fatal "Argument required for build target"
+      exit 1
+    fi
+    build_target "$2"
+    ;;
+  clean)
+    if [[ -d "$build_dir" ]]; then
+      verbose_echo rm -rf "$build_dir"
+    fi
+    ;;
+  *) echo "Unrecognized command $1"; exit 1;;
+esac
+