Delegate to `rbenv-help` for usage, if available

bin/rbenv-install

 #!/usr/bin/env bash
+#
+# Usage: rbenv install [-k|--keep] [-v|--verbose] <version>
+#        rbenv install [-k|--keep] [-v|--verbose] /path/to/definition
+#        rbenv install -l|--list
+#
+#   -l/--list        List all available versions
+#   -k/--keep        Keep source tree in $RBENV_BUILD_ROOT after installation
+#                    (defaults to $RBENV_ROOT/sources)
+#   -v/--verbose     Verbose mode: print compilation status to stdout
+#
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
@@ -15,17 +25,8 @@ fi
 eval "$(ruby-build --lib)"
 
 usage() {
-  { echo "usage: rbenv install [-k|--keep] [-v|--verbose] VERSION"
-    echo "       rbenv install [-k|--keep] [-v|--verbose] /path/to/definition"
-    echo "       rbenv install -l|--list"
-    echo
-    echo "  -l/--list        List all available versions"
-    echo "  -k/--keep        Keep source tree in \$RBENV_BUILD_ROOT after installation"
-    echo "                   (defaults to ${RBENV_ROOT}/sources)"
-    echo "  -v/--verbose     Verbose mode: print compilation status to stdout"
-    echo
-  } >&2
-
+  # We can remove the sed fallback once rbenv 0.4.0 is widely available.
+  rbenv-help installx 2>/dev/null || sed -ne '/^#/!q;s/.//;s/.//;1,2d;p' < "$0"
   [ -z "$1" ] || exit "$1"
 }
 

bin/rbenv-uninstall

 #!/usr/bin/env bash
+#
+# Usage: rbenv uninstall [-f] <version>
+#
+#    -f  Attempt to remove the specified version without prompting
+#        for confirmation. If the version does not exist, do not
+#        display an error message.
+#
+# See `rbenv versions` for a complete list of installed versions.
+#
 set -e
 
 # Provide rbenv completions
@@ -19,15 +28,9 @@ fi
 DEFINITION="$1"
 case "$DEFINITION" in
 "" | -* )
-  { echo "usage: rbenv uninstall [-f] VERSION"
-    echo
-    echo "   -f  Attempt to remove the specified version without prompting"
-    echo "       for confirmation. If the version does not exist, do not"
-    echo "       display an error message."
-    echo
-    echo "Installed versions:"
-    rbenv versions --bare | sed 's/^/  /'
-    echo
+  # 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\}//;1,2d;p' < "$0"
   } >&2
   exit 1
   ;;