How to increase the max pty's on Freebsd 7.0?

Kostik Belousov kostikbel at
Wed Apr 1 13:57:10 PDT 2009

On Wed, Apr 01, 2009 at 10:53:06PM +0200, Ed Schouten wrote:
> Hi Steven,
> * Steven Hartland <killing at> wrote:
> > How can I increase the maximum number or ptys available on FreeBSD 7.0?
> >
> > It seems that currently the machine is maxing out at 512 but there is
> > still loads of capacity left on the machine.
> >
> > Ideally would like to double at least the number of ttys available,
> > any help would be most appreciated.
> You can increase the maximum amount of PTYs by editing a lot of source
> files on your system. There is some good news: in -CURRENT we switched
> to Unix98-style PTYs (/dev/pts/%u). Right now the maximum amount of PTYs
> is limited to 1000 (0 to 999).
> We're currently limited to 7 characters (pts/999) because our utmp/
> wtmp/lastlog files only reserve 8 bytes for the TTY name. If you're
> brave enough, you can increase UT_LINESIZE in include/utmp.h and
> MAXPTSDEVS in sys/kern/tty_pts.c. Be sure to recompile everything and to
> remove your utmp/wtmp/lastlog files.

Can we switch to %x ? Or even, use some radix encoding of the number,
to allow alphabetical symbols too ?
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