by jeff.allen:

What steps will reproduce the problem?

1. go tool 6l -a try.6 | head 

What is the expected output?

Nothing to stderr, no error. Just exit when SIGPIPE arrives as a result of head closing
stdin.

What do you see instead?

go tool 6l: signal 13

Signal 13 is SIGPIPE, used by the OS to tell the writer that the reader isn't listening
anymore, so it might as well just stop writing. Well behaved programs die on SIGPIPE,
silently, because they understand that the later stages of the pipe are asking them to
quit early.

When you run 6l itself, it doesn't complain. The annoying message comes from "go
tool".

In src/cmd/go/tool.go:/^func runTool/ toolCmd.Run() returns an err describing the signal
that the child died from. Perhaps signal 13 should be a special case there? Yuck.

Which compiler are you using (5g, 6g, 8g, gccgo)?

the go cmd

Which operating system are you using?

Linux, 64 bit.

Which version are you using?  (run 'go version')

$ hg id
f2cdaa74b232 tip

Please provide any additional information below.