`export PS1='value'` does not propagate to (Korn) subshells for root?

Please co开发者_运维百科nsider the following /root/.profile:

export PS1=value1
export x=value2

How come the login shell shows the expected prompt (and $x as value2), while the subshells keep showing $x as value2 but $PS1 as '#'? Just in case, I'm trying this under OpenBSD.

[Yeah, I know... What on earth am I doing with OpenBSD if I don't know this? Just toying... in an isolated, most definitely non-production VM =).]

Because your subshells are sourcing something that's resetting PS1.

To debug this, try ksh -x. If that doesn't help, you could try running ksh in strace or an equivalent system call tracing tool.

In case anybody is interested, somebody finally explained this in an OpenBSD mailing list. This behavior is actually expected in OpenBSD, as explained in a comment inside /usr/src/bin/ksh/main.c:

safe_prompt = ksheuid ? "$ " : "# ";
{
    struct tbl *vp = global("PS1");

    /* Set PS1 if it isn't set, or we are root and prompt doesn't
     * contain a # or \$ (only in ksh mode).
     */
    if (!(vp->flag & ISSET) ||
        (!ksheuid && !strchr(str_val(vp), '#') &&
        (Flag(FSH) || !strstr(str_val(vp), "\\$"))))
        /* setstr can't fail here */
        setstr(vp, safe_prompt, KSH_RETURN_ERROR);
}

Check the following files for rogue PS1 assignments.

   /etc/profile
          The  system  wide initialization file, executed for login shells.
   $HOME/.profile
          The personal initialization  file,  executed  for  login  shells
          after /etc/profile.
   $HOME/..kshrc
          Default  personal  initialization file, executed for interactive
          shells when ENV is not set.
   /etc/suid_profile
          Alternative initialization file, executed when instead  of  per-
          sonal  initialization  file  when the real and effective user or
          group id do not match.

There may be a typo in that manpage, it probably meant to say: $HOME/.kshrc