Writability of the source file is requested even when --new file must be written.

[jn0]

I think, if I request a --new file, then the old one is not changed anyway.
Hence, the check for [ -z $EXTERNAL ] is not sufficient.
I'd propose [ -z $EXTERNAL -a -z $NEW ] or something similar.

[jn0]

Too short to make a patch:

diff --git a/mkvdts2ac3.sh b/mkvdts2ac3.sh                                                           
index ffd6414..96d47c0 100755                                                                        
--- a/mkvdts2ac3.sh                                                                                  
+++ b/mkvdts2ac3.sh                                                                                  
@@ -339,7 +339,7 @@ if [ $EXECUTE = 1 ]; then                                                        
        elif [ ! -r "$MKVFILE" ]; then                                                               
                error $"Cannot read '$MKVFILE'."                          
                exit 1                                                                             
-       elif [ -z $EXTERNAL ]; then                                                                  
+       elif [ -z $EXTERNAL ] && [ -z $NEW ]; then                                                   
                if [ ! -w "$MKVFILE" ]; then                                
                        # Only check write permission if we're not keeping the AC3 external
                        error $"Cannot write '$MKVFILE'."                                  

[choekstr]

Great. Love it when people fix their own wishlists. grin