It's like grep for blocks (useful for git spelunking)

block.awk

# Example: git show <treeish> | awk -f block.awk 
# Selectively print sections matching regex in body of matches(), below

function matches(block) {
  return (block ~ /\-\?\>/)
}

/diff/{
  # start of a new block, process the previous
  if (prevblock"" && matches(prevblock)) print prevblock
  prevblock = sep = ""
}

{
  prevblock = prevblock sep $0
  sep = RS
}

END {
  if (prevblock"" && matches(prevblock)) print prevblock
}