remove block of text between two lines based on content

Question

I need to remove/filter a very large log file i managed to bring the log-file into blocks of text starting with a line containing <-- or -->

Answer 1

This might work for you (GNU sed);

sed '/<--\|-->/!b;:a;/Content-Length/!{$!{N;ba}};//{/REGISTER/d}' file

• /<--\|-->/!b if a line does not contain <-- or --> print it
• :a;/Content-Length/!{$!{N;ba}} keep appending lines until the string Content-Length or the end of file is encountered.
• //{/REGISTER/d} if the line(s) read in contains Content-Length and REGISTER delete it/them else print it/them as normal.