Provide CLI usage help on stout/stderr appropriately

When requested via `-h|--help`, usage text should be displayed on stdout
and the exit status should be 0.

When usage text is shown due to invalid arguments, it should be
printed to stderr and exit status should be 1.

bin/rbenv-install

@@ -96,12 +96,12 @@ for option in "${OPTIONS[@]}"; do
     exec ruby-build --version
     ;;
   * )
-    usage 1
+    usage 1 >&2
     ;;
   esac
 done
 
-[ "${#ARGUMENTS[@]}" -le 1 ] || usage 1
+[ "${#ARGUMENTS[@]}" -le 1 ] || usage 1 >&2
 
 unset VERSION_NAME
 
@@ -111,7 +111,7 @@ unset VERSION_NAME
 # version is not specified.
 DEFINITION="${ARGUMENTS[0]}"
 [ -n "$DEFINITION" ] || DEFINITION="$(rbenv-local 2>/dev/null || true)"
-[ -n "$DEFINITION" ] || usage 1
+[ -n "$DEFINITION" ] || usage 1 >&2
 
 # Define `before_install` and `after_install` functions that allow
 # plugin hooks to register a string of code for execution before or

bin/rbenv-uninstall

@@ -33,16 +33,12 @@ if [ "$1" = "-f" ] || [ "$1" = "--force" ]; then
   shift
 fi
 
-[ "$#" -eq 1 ] || usage 1
+[ "$#" -eq 1 ] || usage 1 >&2
 
 DEFINITION="$1"
 case "$DEFINITION" in
 "" | -* )
-  # We can remove the sed fallback once rbenv 0.4.0 is widely available.
-  { rbenv-help uninstall 2>/dev/null ||
-    sed -ne '/^#/!q;s/.\{1,2\}//;1,4d;p' < "$0"
-  } >&2
-  exit 1
+  usage 1 >&2
   ;;
 esac
 

bin/ruby-build

@@ -957,11 +957,9 @@ usage() {
   { version
     echo "usage: ruby-build [-k|--keep] [-v|--verbose] [-p|--patch] definition prefix"
     echo "       ruby-build --definitions"
-  } >&2
+  } >&1
 
-  if [ -z "$1" ]; then
-    exit 1
-  fi
+  [ -z "$1" ] || exit "$1"
 }
 
 list_definitions() {
@@ -992,14 +990,14 @@ parse_options "$@"
 for option in "${OPTIONS[@]}"; do
   case "$option" in
   "h" | "help" )
-    usage without_exiting
+    usage
     { echo
       echo "  -k/--keep        Do not remove source tree after installation"
       echo "  -v/--verbose     Verbose mode: print compilation status to stdout"
       echo "  -p/--patch       Apply a patch from stdin before building"
       echo "  --definitions    List all built-in definitions"
       echo
-    } >&2
+    } >&1
     exit 0
     ;;
   "definitions" )
@@ -1022,11 +1020,11 @@ for option in "${OPTIONS[@]}"; do
   esac
 done
 
-[ "${#ARGUMENTS[@]}" -eq 2 ] || usage 1
+[ "${#ARGUMENTS[@]}" -eq 2 ] || usage 1 >&2
 
 DEFINITION_PATH="${ARGUMENTS[0]}"
 if [ -z "$DEFINITION_PATH" ]; then
-  usage
+  usage 1 >&2
 elif [ ! -f "$DEFINITION_PATH" ]; then
   for DEFINITION_DIR in "${RUBY_BUILD_DEFINITIONS[@]}"; do
     if [ -f "${DEFINITION_DIR}/${DEFINITION_PATH}" ]; then
@@ -1043,7 +1041,7 @@ fi
 
 PREFIX_PATH="${ARGUMENTS[1]}"
 if [ -z "$PREFIX_PATH" ]; then
-  usage
+  usage 1 >&2
 elif [ "${PREFIX_PATH#/}" = "$PREFIX_PATH" ]; then
   PREFIX_PATH="${PWD}/${PREFIX_PATH}"
 fi