AWK script to find number of occurrences of "foo=" in a very large text file (or stream); supplied is a small example of the format one might expect.

example.txt

{
  foo=1
  bar=2
  baz=3
}
{
  foo=0
}
{
}
{
  bar=1
  baz=2
}

firehose.awk

BEGIN { has_foo = 0 }
  
{
  if ( !has_foo && /foo=/ ) has_foo = 1
  
  if ( /^\}/ ) {
    if ( has_foo ) n_foos++
    has_foo = 0
  }
}

END { print n_foos + 0 }

firehose.code

while not eof
  read a line
  if not current_block_has_foo
    if line matches /^\s*foo=/
      current_block_has_foo = true
  if line is "}"
      if current_block_has_foo 
        blocks_with_foo += 1
      current_block_has_foo = false