SUMMARY: TERM limit on Solaris 2.6

From: Chad Rytting (
Date: Thu Feb 25 1999 - 18:14:40 CST

Thanks to:

Casper Dik
Sean Quaint
Dan @

The answer was simple, I just had to get to the faq and read it. The
answer from Casper Dik is posted below.

Thanks for the answers

>I have a question about limits to concurrent logins on Solaris 2.6
>We have a ss20 here that will not allow more than 50 concurrent users
>to be logged in at the same time. Is there some limitation on
>that causes this, or is it a licensing issue that I have to call Sun
>If there is a limitation that needs to be modified, can someone
>help me find where this limit is, and change it to a higher number?

The solaris FAQ says:

3.41) How can I have more than 48 pseudo-ttys?

    Edit /etc/system and add the following line:

        * System V pseudo terminals

        set pt_cnt = <num>

    Halt the system and boot -r.

    You can essentially have as many as you like, but you'll probably
    run into some other limit somewhere. More than 3000 are
    Solaris 2.6 and earlier have telnet/rlogin daemons that do not
    support more than 3844 sessions each. That restriction is lifted
    in Solaris 7.

    Some die-hard system administrator myths as well as some Sun
    documentation claim that you have to increased "sad_cnt", "sadcnt"
    or "nautopush" when adding ptys. There is no truth in this.

    In the unlikely event that you run out of BSD-style ptys,
    you can increase them as well. The maximum here is currently
    176 for pty[p-z][0-9a-f]. This is somewhat less that the BSD
    maximum of 256 limited by 8 bit device minor numbers.

    BSD ttys are awkward to use and all programs I found support SYSV
    ptys without trouble.

        * You don't need this. Increasing this value too much usually
        * just wastes memory.
        * BSD applications never support more than 256 ptys.
        * Solaris 2.x supports no more than 176 BSD ptys.

        set npty = <num>

    But you're not there yet, you also need to edit /etc/iu.ap and
    substitute the new value of "npty-1" for the "47" on the following
    line, in case you do increase the number of BSD style ptys.

                ptsl 0 47 ldterm ttcompat

    Halt the system and boot -r.

    --- end of excerpt from the FAQ

Questions marked with a * or + have been changed or added since
the FAQ was last posted

The most recently posted version of the FAQ is available from

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:13:16 CDT