diff --git a/gallery_dl/option.py b/gallery_dl/option.py
index ecc2ee3d..2194e9e4 100644
--- a/gallery_dl/option.py
+++ b/gallery_dl/option.py
@@ -27,6 +27,15 @@ class ConfigConstAction(argparse.Action):
         namespace.options.append(((self.dest,), self.const))
 
 
+class AppendCommandAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, self.dest, None) or []
+        val = self.const.copy()
+        val["command"] = values
+        items.append(val)
+        setattr(namespace, self.dest, items)
+
+
 class DeprecatedConfigConstAction(argparse.Action):
     """Set argparse const values as config values + deprecation warning"""
     def __call__(self, parser, namespace, values, option_string=None):
@@ -303,6 +312,12 @@ def build_parser():
         action="append_const", const={"name": "zip"},
         help="Store downloaded files in a ZIP archive",
     )
+    postprocessor.add_argument(
+        "--exec",
+        dest="postprocessors", metavar="CMD",
+        action=AppendCommandAction, const={"name": "exec"},
+        help="Execute CMD for each downloaded file",
+    )
     postprocessor.add_argument(
         "--ugoira-conv",
         dest="postprocessors",
diff --git a/gallery_dl/postprocessor/exec.py b/gallery_dl/postprocessor/exec.py
index c86b4805..f4aa971c 100644
--- a/gallery_dl/postprocessor/exec.py
+++ b/gallery_dl/postprocessor/exec.py
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2018 Mike Fährmann
+# Copyright 2018-2019 Mike Fährmann
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
@@ -9,7 +9,9 @@
 """Execute processes"""
 
 from .common import PostProcessor
+from .. import util
 import subprocess
+import shlex
 
 
 class ExecPP(PostProcessor):
@@ -17,27 +19,60 @@ class ExecPP(PostProcessor):
     def __init__(self, pathfmt, options):
         PostProcessor.__init__(self)
 
-        try:
-            self.args = options["command"]
-            self.args[0]  # test if 'args' is subscriptable
-        except (KeyError, IndexError, TypeError):
-            raise TypeError("option 'command' must be a non-empty list")
+        args = options["command"]
+
+        if isinstance(args, str):
+            self.args = util.Formatter(args.replace("{}", "{_temppath}"))
+            self.shell = True
+            self._format = self._format_args_string
+        else:
+            for i, arg in enumerate(args):
+                if "{}" in arg:
+                    args[i] = arg.replace("{}", "{_temppath}")
+            self.args = [util.Formatter(arg) for arg in args]
+            self.shell = False
+            self._format = self._format_args_list
 
         if options.get("async", False):
-            self._exec = subprocess.Popen
+            self._exec = self._exec_async
 
     def run(self, pathfmt):
-        self._exec([
-            arg.format_map(pathfmt.keywords)
-            for arg in self.args
-        ])
+        kwdict = pathfmt.kwdict
+        kwdict["_directory"] = pathfmt.realdirectory
+        kwdict["_filename"] = pathfmt.filename
+        kwdict["_temppath"] = pathfmt.temppath
+        kwdict["_path"] = pathfmt.realpath
+        self._exec(self._format(kwdict))
+
+    def _format_args_list(self, kwdict):
+        return [arg.format_map(kwdict) for arg in self.args]
+
+    def _format_args_string(self, kwdict):
+        return self.args.format_map(_quote(kwdict))
 
     def _exec(self, args):
-        retcode = subprocess.Popen(args).wait()
+        retcode = subprocess.Popen(args, shell=self.shell).wait()
         if retcode:
             self.log.warning(
-                "executing '%s' returned non-zero exit status %d",
-                " ".join(args), retcode)
+                "executing '%s' returned with non-zero exit status (%d)",
+                " ".join(args) if isinstance(args, list) else args, retcode)
+
+    def _exec_async(self, args):
+        subprocess.Popen(args, shell=self.shell)
+
+
+def _quote(kwdict):
+    """Create a copy of 'kwdict' and apply shlex.quote to its string values"""
+    kwdict = kwdict.copy()
+    for key, value in kwdict.items():
+        cls = value.__class__
+        if cls is str:
+            kwdict[key] = shlex.quote(value)
+        elif cls is list:
+            kwdict[key] = shlex.quote(", ".join(value))
+        elif cls is dict:
+            kwdict[key] = _quote(value)
+    return kwdict
 
 
 __postprocessor__ = ExecPP