Update 'computing_htcondor'

computing_htcondor.md

@@ -7,7 +7,6 @@ Basic use, see the manual entry from the command line:
 You can find example submission files in `/auto/work/zhelezov/singularity/batch_centos7` .
 
 
-
 An example .sub file:
 
 ```vim
@@ -91,6 +90,16 @@ condor_submit -file job.sub
 
 ```
 
+You can test your executable or script interactively via:
+
+```
+condor_submit -interactive
+
+```
+which will open a shell on the machine where you can run your executable by hand.
+
+
+
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