turn run-qemu.sh and connect-qemu scripts into buildEnv commands

pkgs/mips-vm/default.nix

@@ -1,11 +1,19 @@
 {
   qemu
+, socat
 , writeShellScriptBin
-, stdenv
+, symlinkJoin
 , lib
-}:
-writeShellScriptBin "mips-vm"
-  ''
+}: let
+  mips-vm = writeShellScriptBin "mips-vm" ''
      export PATH="${lib.makeBinPath [qemu]}:$PATH"
      ${builtins.readFile ./mips-vm.sh}
-  ''
+  '';
+  connect = writeShellScriptBin "connect-vm" ''
+    export PATH="${lib.makeBinPath [socat]}:$PATH"
+    socat -,raw,echo=0,icanon=0,isig=0,icrnl=0,escape=0x0f unix-connect:$1
+  '';
+in symlinkJoin {
+  name = "mips-vm";
+  paths = [ mips-vm connect ];
+}