I have a log-file where at the end of a series of lines you can see if this block is relevant now I'm looking for a command like sed to delete de blocks ending with "Content-Length: 0" and beginning with the last "--" before this line.

I tried sed -n "/--/,/Content-Length: 0/d" but this takes the first "--" and the first "Content-Length: 0" and deletes it.

ex :

line 1 "--"  
line 2   
line 3 "Content-Length: 20"  
line 4 "--"  
line 5  
line 6 "Content-Length: 0" 

i want to delete line 4,5 and 6 not line 1 to 6

hohw can i do this?