diff --git a/README.md b/README.md
index a48ce6c..7ec059b 100644
--- a/README.md
+++ b/README.md
@@ -27,8 +27,9 @@ following keys:
  * :seller      - the seller's (i.e. the entity to be paid) information. This is required
  * :buyer       - the buyer's (i.e. the entity that will pay) information. This is required
  * :items       - a list of items to be paid for
- * :font-path   - (optional) *the path to a font file, e.g. "/usr/share/fonts/truetype/freefont/FreeSans.ttf"
- * :credentials - JIRA and Tempo access credentials. These are needed if the price depends on tracked time
+ * :credentials - (optional) JIRA and Tempo access credentials. These are needed if the price depends on tracked time
+ * :font-path   - (optional) the path to a font file, e.g. "/usr/share/fonts/truetype/freefont/FreeSans.ttf"
+ * :callbacks   - (optional) a list of commands to be called with the resulting pdf file
 
 See `resources/config.edn` for an example configuration.
 
@@ -118,3 +119,22 @@ If a confirmation email is to be sent, a :smtp key must also be provided, e.g.:
 Each invoice can also be sent via email to the appropriate seller. For this to work, both the seller
 and the buyer must have an :email key set and the credentials must contain a :smtp key with the
 :smtp settings for the email server.
+
+
+## Callbacks
+
+A list of additional commands can be added to each invoice. Each command will be called with
+the generated invoice as its final parameter, e.g.
+
+    {:seller {...}
+     :buyer {...}
+     :items [...]
+     :callbacks [["ls" "-l"] ["rm"] ["du" "-sh"]]}
+
+Will call the following commands (assuming that the generated invoice is `/path/to/file.pdf`):
+
+    ls -l /path/to/file.pdf
+    du -sh /path/to/file.pdf
+    rm /path/to/file.pdf
+
+The last one will obviously fail, as the file no longer exists, and the error message will be displayed
diff --git a/src/invoices/core.clj b/src/invoices/core.clj
index fc48a5b..950de09 100644
--- a/src/invoices/core.clj
+++ b/src/invoices/core.clj
@@ -4,6 +4,7 @@
             [invoices.jira :refer [prev-timesheet prev-month]]
             [clojure.tools.cli :refer [parse-opts]]
             [clojure.string :as str]
+            [clojure.java.shell :refer [sh]]
             [postal.core :refer [send-message]])
   (:gen-class))
 
@@ -49,20 +50,36 @@
      :error (= :SUCCESS)
      (println " - email sent: "))))
 
+(defn run-callback [file callback]
+  (let [command (concat callback [file])
+        str-command (str/join " " command)
+        result (apply sh command)]
+    (if (= (:exit result) 0)
+      (println "    *" str-command)
+      (println "    X" str-command ":\n" (:err result)))
+    (assoc result :command str-command)))
+
+(defn run-callbacks [invoice callbacks]
+  (doall (map (partial run-callback invoice) callbacks)))
+
 (defn date-applies? [when {to :to from :from}]
   (and (or (nil? to) (-> when .toString (compare to) (< 0)))
        (or (nil? from) (-> when .toString (compare from) (>= 0)))))
 
-(defn for-month [when {seller :seller buyer :buyer items :items creds :credentials font-path :font-path} & [number]]
-  (->>
-   (pdf/render seller buyer
-               (->> items
-                    (filter (partial date-applies? when))
-                    (map (partial set-price (prev-timesheet when creds))))
-               (pdf/last-working-day when)
-               (invoice-number when number)
-               font-path)
-   (send-email (:email buyer) (:email seller) creds)))
+
+(defn render-month [when {seller :seller buyer :buyer items :items creds :credentials font-path :font-path} number]
+  (pdf/render seller buyer
+              (->> items
+                   (filter (partial date-applies? when))
+                   (map (partial set-price (prev-timesheet when creds))))
+              (pdf/last-working-day when)
+              (invoice-number when number)
+              font-path))
+
+(defn for-month [when {seller :seller buyer :buyer creds :credentials callbacks :callbacks :as invoice} & [number]]
+  (let [file (-> when (render-month invoice number) (str ".pdf") java.io.File. .getAbsolutePath)]
+    (send-email (:email buyer) (:email seller) creds file)
+    (run-callbacks file callbacks)))
 
 (defn get-invoices [nips config]
   (if (seq nips)
@@ -95,7 +112,7 @@
        (exit 0)))
 
 (defn -main
-  "I don't do a whole lot ... yet."
+  "Generate invoice pdfs"
   [& args]
   (let [{:keys [options arguments errors summary]} (parse-opts args cli-options)]
     (cond
@@ -104,5 +121,6 @@
       (not= 1 (count arguments)) (exit -1 "No config file provided"))
     (println "Generating invoices")
     (doseq [[i invoice] (map-indexed vector (get-invoices (:company options) (first arguments)))]
-      (for-month (:when options) invoice (+ i (:number options))))
-    ))
+      (for-month (:when options) invoice (+ i (:number options)))
+      (println)))
+  (shutdown-agents))