diff --git a/setup.py b/setup.py
index 1f10c44ae..86517d67e 100644
--- a/setup.py
+++ b/setup.py
@@ -142,6 +142,8 @@ def run(self):
 fail_if = sos.actions:fail_if
 warn_if = sos.actions:warn_if
 stop_if = sos.actions:stop_if
+done_if = sos.actions:done_if
+skip_if = sos.actions:skip_if
 download = sos.actions:download
 run = sos.actions:run
 
diff --git a/src/sos/actions.py b/src/sos/actions.py
index 57e13d616..2ef6574df 100644
--- a/src/sos/actions.py
+++ b/src/sos/actions.py
@@ -622,6 +622,22 @@ def stop_if(expr, msg='', no_output=False):
         raise StopInputGroup(msg=msg, keep_output=not no_output)
     return 0
 
+@SoS_Action(acceptable_args=['expr', 'msg'])
+def done_if(expr, msg=''):
+    '''Assuming that output has already been generated and stop
+     executing the rest of the substep'''
+    if expr:
+        raise StopInputGroup(msg=msg, keep_output=True)
+    return 0
+
+@SoS_Action(acceptable_args=['expr', 'msg', 'no_output'])
+def skip_if(expr, msg=''):
+    '''Skip the current substep and set _output to empty. Output
+    will be removed if already generated.'''
+    if expr:
+        raise StopInputGroup(msg=msg, keep_output=False)
+    return 0
+
 #
 # download file with progress bar
 #