diff --git a/README.md b/README.md
index 191a0565..5dcc97de 100644
--- a/README.md
+++ b/README.md
@@ -71,18 +71,16 @@ bb [ --help ] [ -i ] [ -o ] [ -io ] [ --version ] [ -f <file> ] [ expression ]
 
 Type `bb --help` to see a full explanation of the options.
 
-There is one special variable, `*in*`, which is the input read from stdin. The
-input is read as EDN by default. If the `-i` flag is provided, then the input is
-read as a string which is then split on newlines. The output is printed as EDN
-by default, unless the `-o` flag is provided, then the output is turned into
-shell-scripting friendly output. To combine `-i` and `-o` you can use `-io`.
+The input is read as EDN by default. If the `-i` flag is provided, then the
+input is read as a string which is then split on newlines. The output is printed
+as EDN by default, unless the `-o` flag is provided, then the output is turned
+into shell-scripting friendly output. To combine `-i` and `-o` you can use
+`-io`.
 
 The current version can be printed with `bb --version`.
 
-Currently only the following special forms/macros are supported: anonymous
-function literals like `#(%1 %2)`, `quote`, `do`,`if`, `when`, `let`, `and`,
-`or`, `->`, `->>`, `as->`. Anonymous functions literals are allowed with
-currently up to three positional arguments.
+Babashka supports a subset of Clojure which is interpreted by
+[sci](https://github.com/borkdude/sci).
 
 The `clojure.core` functions are accessible without a namespace alias.
 
@@ -96,7 +94,12 @@ through the aliases:
 
 From Java the following is available:
 
-- `System`: `getProperty`, `getProperties`, `getenv`
+- `System`: `exit`, `getProperty`, `getProperties`, `getenv`
+
+Special vars:
+
+- `*in*`: contains the input read from stdin
+- `*command-line-args*`: contain the command line args
 
 Examples:
 
@@ -143,13 +146,26 @@ bb -f script.clj
 Using `bb` with a shebang also works:
 
 ``` shellsession
-$ cat script.clj
-#!/usr/bin/env bb -f
+#!/usr/bin/env bb -io -f
 
-(+ 1 2 3)
+(defn get-url [url]
+  (println "Fetching url:" url)
+  (let [{:keys [:exit :err :out]} (shell/sh "curl" "-sS" url)]
+    (if (zero? exit) out
+      (do (println "ERROR:" err)
+          (System/exit 1)))))
 
-$ ./script.clj
-6
+(defn write-html [file html]
+  (println "Writing html to" file)
+  (spit file html))
+
+(let [[url file] *command-line-args*]
+  (when (or (empty? url) (empty? file))
+    (println "Usage: <url> <file>")
+    (System/exit 1))
+  (write-html file (get-url url)))
+
+(System/exit 0)
 ```
 
 ## Test
diff --git a/project.clj b/project.clj
index 9c32dd35..650113a0 100644
--- a/project.clj
+++ b/project.clj
@@ -9,7 +9,7 @@
             :url "http://opensource.org/licenses/eclipse-1.0.php"}
   :source-paths ["src"]
   :dependencies [[org.clojure/clojure "1.9.0"]
-                 [borkdude/sci "0.0.4"]]
+                 [borkdude/sci "0.0.7-SNAPSHOT"]]
   :profiles {:clojure-1.9.0 {:dependencies [[org.clojure/clojure "1.9.0"]]}
              :clojure-1.10.1 {:dependencies [[org.clojure/clojure "1.10.1"]]}
              :test {:dependencies [[clj-commons/conch "0.9.2"]]}
diff --git a/src/babashka/main.clj b/src/babashka/main.clj
index f02a0f19..e62e3411 100644
--- a/src/babashka/main.clj
+++ b/src/babashka/main.clj
@@ -4,7 +4,7 @@
    [clojure.edn :as edn]
    [clojure.java.io :as io]
    [clojure.java.shell :as shell]
-   [clojure.string :as str :refer [starts-with?]]
+   [clojure.string :as str]
    [sci.core :as sci])
   (:gen-class))
 
@@ -20,33 +20,34 @@
 
 (defn- parse-opts [options]
   (let [opts (loop [options options
-                    opts-map {}
-                    current-opt nil]
+                    opts-map {}]
                (if-let [opt (first options)]
-                 (if (starts-with? opt "-")
-                   (recur (rest options)
-                          (assoc opts-map opt [])
-                          opt)
-                   (recur (rest options)
-                          (update opts-map current-opt conj opt)
-                          current-opt))
-                 opts-map))
-        version (boolean (get opts "--version"))
-        raw-in (boolean (or (get opts "--raw")
-                            (get opts "-i")
-                            (get opts "-io")))
-        raw-out (boolean (or (get opts "-o")
-                             (get opts "-io")))
-        println? (boolean (get opts "--println"))
-        help? (boolean (get opts "--help"))
-        file (first (or (get opts "-f")
-                        (get opts "--file")))]
-    {:version version
-     :raw-in raw-in
-     :raw-out raw-out
-     :println? println?
-     :help? help?
-     :file file}))
+                 (case opt
+                   ("--version") {:version true}
+                   ("--help") {:help? true}
+                   ("-i") (recur (rest options)
+                                 (assoc opts-map
+                                        :raw-in true))
+                   ("-o") (recur (rest options)
+                                 (assoc opts-map
+                                        :raw-out true))
+                   ("-io") (recur (rest options)
+                                  (assoc opts-map
+                                         :raw-in true
+                                         :raw-out true))
+                   ("-f" "--file")
+                   (let [options (rest options)]
+                     (recur (rest options)
+                            (assoc opts-map
+                                   :file (first options))))
+                   (if (not (:file opts-map))
+                     (assoc opts-map
+                            :expression opt
+                            :command-line-args (rest options))
+                     (assoc opts-map
+                            :command-line-args options)))
+                 opts-map))]
+    opts))
 
 (defn parse-shell-string [s]
   (str/split s #"\n"))
@@ -54,7 +55,7 @@
 (defn print-version []
   (println (str "babashka v"(str/trim (slurp (io/resource "BABASHKA_VERSION"))))))
 
-(def usage-string "Usage: [ --help ] [ -i ] [ -o ] [ -io ] [ --version ] [ expression ]")
+(def usage-string "Usage: [ --help ] | [ --version ] | [ -i ] [ -o ] [ -io ]  ( expression | -f <fie> )")
 (defn print-usage []
   (println usage-string))
 
@@ -76,10 +77,13 @@
 "))
 
 (defn read-file [file]
-  (as-> (slurp file) x
-    ;; remove hashbang
-    (str/replace x #"^#!.*" "")
-    (format "(do %s)" x)))
+  (let [f (io/file file)]
+    (if (.exists f)
+      (as-> (slurp file) x
+        ;; remove hashbang
+        (str/replace x #"^#!.*" "")
+        (format "(do %s)" x))
+      (throw (Exception. (str "File does not exist: " file))))))
 
 (defn get-env
   ([] (System/getenv))
@@ -94,10 +98,15 @@
 (defn get-properties []
   (System/getProperties))
 
+(defn exit [n]
+  (System/exit n))
+
 (def bindings
   {'run! run!
    'shell/sh shell/sh
    'csh shell/sh ;; backwards compatibility, deprecated
+   'slurp slurp
+   'spit spit
    'pmap pmap
    'print print
    'pr-str pr-str
@@ -106,13 +115,19 @@
    'edn/read-string edn/read-string
    'System/getenv get-env
    'System/getProperty get-property
-   'System/getProperties get-properties})
+   'System/getProperties get-properties
+   'System/exit exit})
 
 (defn main
   [& args]
+  #_(binding [*out* *err*]
+    (prn ">> args" args))
   (or
    (let [{:keys [:version :raw-in :raw-out :println?
-                 :help? :file]} (parse-opts args)]
+                 :help? :file :command-line-args
+                 :expression] :as _opts} (parse-opts args)]
+     #_(binding [*out* *err*]
+       (prn ">>" _opts))
      (second
       (cond version
             [(print-version) 0]
@@ -120,30 +135,30 @@
             [(print-help) 0]
             :else
             (try
-              [(let [exprs (drop-while #(str/starts-with? % "-") args)
-                     _ (when-not (or (= 1 (count exprs)) file)
-                         (throw (Exception. ^String usage-string)))
-                     expr (if file (read-file file) (last args))
-                     in (delay (let [in (slurp *in*)]
-                                 (if raw-in
-                                   (parse-shell-string in)
-                                   (read-edn in))))
-                     res (sci/eval-string
-                          expr
-                          {:bindings (assoc bindings
-                                            (with-meta '*in*
-                                              {:sci/deref! true}) in)})]
-                 (if raw-out
-                   (if (coll? res)
-                     (doseq [l res]
-                       (println l))
-                     (println res))
-                   ((if println? println? prn) res))) 0]
+              [(do (when-not (or expression file)
+                     (throw (Exception. "Missing expression.")))
+                 (let [expr (if file (read-file file) expression)
+                       in (delay (let [in (slurp *in*)]
+                                   (if raw-in
+                                     (parse-shell-string in)
+                                     (read-edn in))))
+                       res (sci/eval-string
+                            expr
+                            {:bindings (assoc bindings
+                                              (with-meta '*in*
+                                                {:sci/deref! true}) in
+                                              '*command-line-args* command-line-args)})]
+                   (if raw-out
+                     (if (coll? res)
+                       (doseq [l res]
+                         (println l))
+                       (println res))
+                     ((if println? println? prn) res)))) 0]
               (catch Exception e
                 (binding [*out* *err*]
-                  (println (str/trim
-                            (or (:stderr (ex-data e))
-                                (.getMessage e))) ))
+                  (when-let [msg (or (:stderr (ex-data e))
+                                     (.getMessage e))]
+                    (println (str/trim msg) )))
                 [nil 1])))))
    1))
 
diff --git a/test/babashka/main_test.clj b/test/babashka/main_test.clj
index e787dd13..6ff5fcdb 100644
--- a/test/babashka/main_test.clj
+++ b/test/babashka/main_test.clj
@@ -26,7 +26,7 @@
   (testing "fn"
     (is (= 2 (bb 1 "(#(+ 1 %) *in*)")))
     (is (= [1 2 3] (bb 1 "(map #(+ 1 %) [0 1 2])")))
-    (is (bb 1 "(#(when (odd? *in*) *in*) 1)")))
+    (is (= 1 (bb 1 "(#(when (odd? *in*) *in*))"))))
   (testing "map"
     (is (= [1 2 3] (bb 1 '(map inc [0 1 2])))))
   (testing "keep"
@@ -69,3 +69,9 @@
     (is (= "bar" (second res)))
     (doseq [s res]
       (is (not-empty s)))))
+
+(deftest malformed-command-line-args
+  (is (thrown-with-msg? Exception #"File does not exist: non-existing\n"
+                        (bb nil  "-f" "non-existing")))
+  (is (thrown-with-msg? Exception #"Missing expression.\n"
+                        (bb nil))))
diff --git a/test/babashka/test_utils.clj b/test/babashka/test_utils.clj
index 4f73ffef..2caba366 100644
--- a/test/babashka/test_utils.clj
+++ b/test/babashka/test_utils.clj
@@ -6,19 +6,25 @@
 (set! *warn-on-reflection* true)
 
 (defn bb-jvm [input & args]
-  (with-out-str
-    (if input
-      (with-in-str input
-        (apply main/main args))
-      (apply main/main input args))))
+  (let [sw (java.io.StringWriter.)
+        res (binding [*err* sw]
+              (with-out-str
+                (if input
+                  (with-in-str input
+                    (apply main/main args))
+                  (apply main/main input args))))]
+    (if-let [err ^String  (not-empty (str sw))]
+      (throw (Exception. err)) res)))
 
 (defn bb-native [input & args]
   (let-programs [bb "./bb"]
-    (binding [sh/*throw* false]
-      (if input
-        (apply bb (conj (vec args)
-                        {:in input}))
-        (apply bb input args)))))
+    (try (if input
+           (apply bb (conj (vec args)
+                           {:in input}))
+           (apply bb input args))
+         (catch Exception e
+           (let [err-msg (or (:stderr (ex-data e)) "")]
+             (throw (Exception. ^String err-msg)))))))
 
 (def bb
   (case (System/getenv "BABASHKA_TEST_ENV")