How to write to /var/log/system.log on a Mac

I am tailing the system.log on a mac:

tail -f -n 0 /var/log/system.log

but I can't figure out how to write to this log. It does seem to be the main log on the machine. I tried:

logger foobar  # didn't work
syslog -s -l error "message to send"  # didn't work

anyone know how to write to the system.log on a Mac?

update:

if I run: log stream

and then use:

logger -is -t krypted "Hello L"

it will show up in the stream, but not in /var/log/system.log. weird.