ab apache benchmark tool to send post data but not from file

Question

I'm using ab from apache2-utils for benchmarking purposes like:

ab -c 2 -n 200 -p file.txt -T application/json url

. Is there any way to do the same, but not reading the content from a file, but from a parameter? Or environment variable or something? So, to run the benchmark tool, but avoiding the need for an external file.