do not use pseudo-tty if redirecting to file

capture.sh

@@ -39,7 +39,7 @@ EOF
 trap 'info' EXIT
 
 exec 2> >(tee -a "$DAT" "$ERR")
-if which socat 1>/dev/null 2>&1 && ! [ "$PROG" = "sudo" ]
+if [ -t 1 ] && ! [ "$PROG" = "sudo" ] && which socat 1>/dev/null 2>&1
 then
 	socat PTY,rawer,link="$PTYA" PTY,rawer,link="$PTYB" &
 	socat="$!"