I used to echo something to /proc/1/fd/1 in order to see that something to show up in the log.
And this works even now, but… have you got any best practice to doing the same while using the old INITSYSTEM?
The INITSYSTEM functionality has been completely removed in latest balenaOS release, as shown on
https://www.balena.io/docs/reference/base-images/base-images/#major-changes, but everyone, just like me, is free to bring it back into action as shown on https://www.balena.io/docs/reference/base-images/base-images/#installing-your-own-initsystem.
The side effect seems to be chat echoing something to /proc/1/fd/1 does not work anymore, since that file descriptor seems to be linked to /dev/null within /proc.