You can reload the ttys file by sending SIGHUP to the init process.
init(8) mentions this but ttys(5) does not, which can be confusing for
users who don't know that. I've added a note to this effect to ttys(5)
referencing init(8).
Index: ttys.5
===================================================================
RCS file: /cvs/src/libexec/getty/ttys.5,v
retrieving revision 1.11
diff -u -p -r1.11 ttys.5
--- ttys.5 22 Oct 2008 22:16:16 -0000 1.11
+++ ttys.5 23 Sep 2018 20:21:23 -0000
@@ -129,6 +129,15 @@ may be followed by a quoted command stri
will execute
.Em before
starting the command specified by the second field.
+.El
+.Pp
+Changes to the ttys file will not take effect until it is reloaded by
+.Xr init 8 ,
+which can be triggered without a reboot by sending it a terminal line
hangup
+(HUP) signal. See the
+.Xr init 8
+man page for more information.
+
.Sh FILES
.Bl -tag -width /etc/ttys -compact
.It Pa /etc/ttys
