Using pipes as serial port for VirtualBox
While trying to reproduce and debug UnionFS bugs with VirtualBox, I needed to extract a copy of the call traces. Screenshots are not easily usable, so I tried the "serial ports" feature of VirtualBox.
An "Host Pipe" mode is available, to redirect serial port output to a pipe. But it didn't work by using a named pipe, created with mkfifo. Actually, if set to create the pipe, VirtualBox will create a UNIX local domain socket.
$ file /tmp/vbox-pipe
The "pipe" name is a bit ambiguous, it's easy to understand it as a fifo, not a socket (and actually, the Windows implementation uses a named pipe in VirtualBox...)