Magic BSD grep

# Let's start with the good old debian
root@debian:~# echo -e 'hello\ntest\ntest test' | grep '.*\s.*'
test test
root@debian:~# echo -e 'hello\ntest\ntest test' | grep '\s'
test test

# So far so good, let's switch to the FreeBSD box
[root@freebsd ~]# echo -e 'hello\ntest\ntest test' | grep '.*\s.*'
test test
[root@freebsd ~]# echo -e 'hello\ntest\ntest test' | grep '\s'
test
test test

# Wtf is that 'test' match in the last command? Looks as if it matches plain 's' in this case.
# Lets try some switches. According to the man, the sensible ones are only -P, -F and -E, but -P is not supported
[root@freebsd ~]# echo -e 'hello\ntest\ntest test' | grep -P '\s'
grep: The -P option is not supported
[root@freebsd ~]# echo -e 'hello\ntest\ntest test' | grep -E '\s'
test
test test