Add multi-module release launcher example

examples/multi-module/select-module.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+set -eu
+
+usage() {
+  echo "usage: select-module.sh selector|tag VALUE" >&2
+  exit 2
+}
+
+[ "$#" -eq 2 ] || usage
+mode=$1
+value=$2
+case "$mode" in
+  selector|tag) ;;
+  *) usage ;;
+esac
+
+script_dir=$(CDPATH= cd "$(dirname "$0")" && pwd)
+mapping=${RELEASEKIT_MODULE_MAP:-$script_dir/release-modules.tsv}
+[ -f "$mapping" ] || { echo "module map not found: $mapping" >&2; exit 2; }
+
+tab=$(printf '\t')
+matches=0
+selected_selector=
+selected_pattern=
+selected_module=
+selected_profile=
+
+while IFS="$tab" read -r selector pattern module profile || [ -n "${selector:-}${pattern:-}${module:-}${profile:-}" ]; do
+  case "${selector:-}" in
+    ''|\#*) continue ;;
+  esac
+  fields=$(awk -F '\t' '{ print NF }' <<EOF
+$selector$tab$pattern$tab$module$tab$profile
+EOF
+)
+  [ "$fields" -eq 4 ] || { echo "module map row must have four tab-separated fields" >&2; exit 2; }
+  [ -n "$pattern" ] && [ -n "$module" ] && [ -n "$profile" ] || {
+    echo "module map row has an empty field for selector $selector" >&2
+    exit 2
+  }
+
+  matched=false
+  if [ "$mode" = selector ]; then
+    [ "$selector" = "$value" ] && matched=true
+  else
+    # The value remains a shell pattern in this case statement; it is never eval'd.
+    case "$value" in
+      $pattern) matched=true ;;
+    esac
+  fi
+  if [ "$matched" = true ]; then
+    matches=$((matches + 1))
+    selected_selector=$selector
+    selected_pattern=$pattern
+    selected_module=$module
+    selected_profile=$profile
+  fi
+done < "$mapping"
+
+if [ "$matches" -ne 1 ]; then
+  if [ "$matches" -eq 0 ]; then
+    echo "no module map row matches $mode $value" >&2
+  else
+    echo "module map has ambiguous rows for $mode $value" >&2
+  fi
+  exit 2
+fi
+
+printf '%s\t%s\t%s\t%s\n' \
+  "$selected_selector" "$selected_pattern" "$selected_module" "$selected_profile"