From: Martin Pitt <martin@piware.de>
Date: Sun, 29 Aug 2021 07:29:34 +0000 (+0200)
Subject: vm: More precise "free port" detection
X-Git-Url: https://piware.de/gitweb/?p=bin.git;a=commitdiff_plain;h=35f89c0ca5276c3fa939e2cba92068ae1d123c11

vm: More precise "free port" detection

22000 is used by syncthing, and it resets the connection. Specifically
search for a refused connection.
---

diff --git a/vm b/vm
index 0f14fea..5323132 100755
--- a/vm
+++ b/vm
@@ -5,7 +5,7 @@ image="$1"
 shift
 # determine ssh forward port
 ssh_port=22000
-while echo '' | nc localhost $ssh_port >/dev/null; do
+until echo '' | nc localhost $ssh_port 2>&1 >/dev/null | grep -q 'Connection refused'; do
     ssh_port=$((ssh_port+1))
 done
 echo "Host ssh port: $ssh_port"