Re: [PATCH net] selftests: net: move amt to socat for better compatibility

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 09 May 2024 19:39:36 +0200 Paolo Abeni wrote:
> Acked-by: Paolo Abeni<pabeni@redhat.com>

Thanks!

> As a minor note, shell variable expansion should already trim all the
> trailing/leading spaces from the socat command output, so it should not
> be necessary replace the string comparison with the grep command:
> 
> 	RESULT6=$(ip netns exec "${LISTENER}" timeout 15 socat - UDP6-LISTEN:6000,readbytes=128 || true)
> 	if [ "$RESULT6" == "2001:db8:3::2" ]; then

99% sure I tried that exact thing, but it wasn't enough.

$ msg=$(socat - UDP4-LISTEN:1234,readbytes=128)
$ echo ">$msg<"
>127.0.0.1                                                                                                                       <
$ msg=$msg
$ echo ">$msg<"
>127.0.0.1                                                                                                                       <
$ msg=$(echo $msg)
$ echo ">$msg<"
>127.0.0.1<


IOW we'd need to feed it thru an echo or some such.
Possibly something like: [ $(echo $msg) == "127.0.0.1" ]
But I personally find that a touch too magical.
The grep works 🤷️