This hung:

# looker $(svcs -L sled-agent)
^C

The file does exist:

# tail -1 $(svcs -L sled-agent) | looker
08:46:50.175Z WARN SledAgent: failed to notify nexus about sled agent: no record found for Query { name: Name("_nexus._tcp.control-plane.oxide.internal."), query_type: AAAA, query_class: IN }, will retry in 1.040373496s

I think there are a few things here:

• If looker doesn't accept files on the command line, presumably this should be a syntax error? Unless it interpreted the file as a valid value for some other argument?
• It would be nice if it did accept files on the command line
• Either way, if it's going to read from stdin and stdin is a tty, how about printing a warning message like "note: reading from stdin, which is a tty"? I don't think this is common, but I've seen a bunch of tools do it and I don't know of any downside.