Adds usage().

Author: beporter

nfsexports-setsudoaccess

@@ -1,8 +1,33 @@
 #!/usr/bin/env bash
 
+#---------------------------------------------------------------------
+usage ()
+{
+	cat <<EOT
+
+${0##*/}
+    Script to inject the proper command exceptions into a system's
+    /etc/sudoers file to allow vagrant to modify /etc/exports for
+    NFS shared folder use without prompting the user for an
+    administrator password during \`vagrant up\`.
+    See: https://docs.vagrantup.com/v2/synced-folders/nfs.html
+    Has no effect if run repeatedly.
+
+Usage:
+    bin/${0##*/}
+
+
+EOT
+
+	exit 0
+}
+if [ "$1" = '-h' ]; then
+	usage
+fi
+
 # Make sure only root can run our script
 if [[ $EUID -ne 0 ]]; then
-   echo "This script must be run using sudo" 1>&2
+   echo "!! This script must be run using sudo." 1>&2
    exit 1
 fi