use |&.

I already know that, but "tools behave differently" is the point

All the tools print help messages to stderr. That is consistent.

Have you checked:
go tool compile --help | grep -i debug
go tool link --help | grep -i debug
are you sure?

@mvdan is right, this is standard for all command line tools and the flag package when outputting usage information.

Usage statements should by default be written in standard error output. You may check this article’s secrion “Where” for more information.

Closing. Merry Christmas! 🎄🎅🎁

I think @jfcg has a point here, though - all the tools use stderr for usage messages, yet go tool compile seems to use stdout:

$ go tool compile
[usage text]
$ go tool compile >/dev/null

Let's keep this issue open for that inconsistency.

I cannot see a good reason why it would, and it seems like it has always printed to stdout since it was created in 2015 from all the separate compilers - will give this a go for 1.11.

Change https://golang.org/cl/85418 mentions this issue: cmd/compile: print usage to stderr for consistency