Repeating weird error message on host but doesn't affect syncing

[louy2]

Unison 2.48.4 Host is Windows 10 Guest is Alpine Linux 3.6 Engine is VirtualBox

The system cannot find the path specified.
The system cannot find the path specified.
Unison not running in VM

Despite the message syncing is fine. The message would repeat in exactly that order and counts.

Relevant code is at command.rb:98:

total_mem = `#{ssh_command_text} 'free -m | egrep "^Mem:" | awk "{print \\$2}"' 2>/dev/null`
_unison_proc_returnval = (
    `#{ssh_command_text} 'ps aux | grep "[u]nison -server" | awk "{print \\$2, \\$4}"' 2>/dev/null`
)
if _unison_proc_returnval == ''
    puts "Unison not running in VM"
    next
end

For some reason that thread cannot find my ssh. Weird.

[louy2]

After some experiments, I found the culprit: /dev/null. Unfortunately for backtick Ruby executes the command under Windows cmd, not POSIX.