Re: [Expectperl-discuss] Please point me to the right mailing list

[Carlyle S. <car...@db...>]

I answered all your comments including the mention of ptsname().

Roland Giersig <rgi...@cp...> wrote on 06.02.2008 16:56:30:

> Carlyle Sutphen wrote:
> > Thank you for picking this up.
> >
> > No, I can't install IO::Tty. I would have to justify rolling out
> non-standard packages on many
> > hundreds of servers.
>
> Comparing "rolling out a self-written custom script that probably
> doesn't has an automatic testsuite" to "installing a proven-in-use
> module" I fail to see the problem... :-) (don't flame me, I know,
> company policies... *sigh*)

Yes, we just don't fight global engineering any more :(
The testing is not automized, true, but the scripts we roll out
generally never get developed any further. The are written to
do a simple task and last forever or until an OS upgrade breaks them.

>
> > But if I can't get this to fly, I may look at PAR.
>
> What I meant was installing the module in a private lib-dir. And yes,
> then you can package this up with PAR.

I understood that. Sounds good. I will certainly look into that at least
for future use.

>
> > I only need the slave side (pts) name. I'm sure it must be
> something simple. The rest
> > works fine.
>
> No, I don't think it can be done with pure perl. In C you have ptsname()
> for that purpose, but as it is not POSIX there is no standard perl
> binding to that that I am aware of (other than in IO::Tty).
>
> Generally speaking, pty handling is a black magic and VERY system-dependent.
>
> But come to think of, I have a nifty work-around! Use "ssh -t localhost
> cmd" to spawn the command with a terminal as stdin/out and interact with
> that via open2() or open3(). How does that sound?

I'll try that but it sounds too simple, it can't work ;-P

>
> Hope this helps,
>
> Roland
>
> > Here is the relevant code:
> >
> > #!/usr/bin/perl -w
> > use strict;
> > use Fcntl; # Needed for O_RDWR and O_NOCTTY flags to sysopen
> > use POSIX qw/setsid ttyname/;
> > use POSIX ":sys_wait_h";
> > #
> > # Set up my variables and read the command line parameters.
> > #
> > # Open the control side and set non blocking
> > sysopen( PTC, "/dev/ptc", O_RDWR | O_NOCTTY ) or die "Can't open a
> pseudo-terminal. $!";
> > $s = select(PTC); $| = 1; select($s);
> > # Get the name of the slave side
>
> That won't work, you need ptsname() here. That this works in AIX is...
> well, I can't say non-standard, because there is no standard... :-)

I saw that. I also found something else:
####################
sub ptsname {
  my $fd = shift;

  my $name = '/dev/pts/';
  my $pty;

  unless( ioctl( \*$fd, &TIOCGPTN, $pty ) ) {
    unless( ioctl( \*$fd, &DEF_TIOCGPTN, $pty ) ) {
      ioctl( \*$fd, &TIOCGPTN|0x00040000, $pty );
    }
  }

  $pty = ord(unpack("A", $pty));

  return $name.$pty;
}
####################

For my purpose I would drop the GLOB ref. But how do I get the defines from
unistd.h into variables my perl script. Then I could replace the function refs.

>
> > $ptyname = ttyname(fileno(PTC)) or die "Cannot get slave name: $?, $!\n";
> > $pid = fork;
> > if ($pid < 0) {
> >  die "Can't fork: $1\n";
> > }
> > if( $pid == 0 ) { # I'm the son ; exec the program...
> >   # Break away from the old controling terminal.
> >   setsid() or die "Can't setsid: $!\n";
> >   # Open the slave side of the new one and set non-blocking IO
> >   sysopen( PTS, $ptyname, O_RDWR ) or die "Can't open a pseudo-
> terminal (child). $!";
> >   $s = select(PTS); $| = 1; select($s);
> >   close STDIN;
> >   close STDOUT;
> >   close STDERR;
> >   open(STDIN,"<&PTS");
> >   open(STDOUT,">&PTS");
> >   open(STDERR,">&STDOUT");
> >   $| = 1;
> >   exec $prog-needing-tty;
> > }
> > $| = 1;
> > while( sysread(PTC, $_, 1) ) {
> >     print "$_";
> >     $buf = $buf . $_;
> >     #
> >     # Check for specific string from child
> >     # and send the correct responses.
> >     #
> >     if( ($kid = waitpid(-1, WNOHANG)) > 0 ) {
> >         last;
> >     }
> > }
> > # Cleanup and exit
> >
> >
> > Regards,
> > Carlyle.
> >
> > Roland Giersig <rgi...@cp...> wrote on 06.02.2008 14:47:49:
> >
> >> Can you post the relevant parts of the script?
> >>
> >> PTY-handling is hard, that's why IO::Tty is doing it in C. And you have
> >> no way of installing IO::Tty locally? If you worry about distribution,
> >> have a look at PAR, the Perl Archiver, on CPAN which lets you package
> >> required modules, even binary ones, with your script.
> >>
> >> Servus, Roland
> >>
> >> Carlyle Sutphen wrote:
> >>> Hello,
> >>>
> >>> I am a system administrator in a large corporation which
> >>> has not included Expect.pm and its siblings IO::Tty and IO::Stty
> >>> in the packaging.
> >>>
> >>> I have written a perl script which creates a terminal for a child
> >>> process which uses the terminal rather than standard IO;
> >>> much as expect does but very simply and of very limited
> >>> scope.
> >>>
> >>> This script works fine on AIX but not on SunOS or Linux.
> >>>
> >>> I need to know how to get the name of the slave side after
> >>> opening the control side (/dev/ptc on AIX and /dev/ptmx on
> >>> the others). On AIX ttyname does this for me but it returns
> >>> "Inappropriate ioctl for device" elsewhere.
> >>>
> >>> I don't mean to take up time and space on this list but I have been
> >>> looking unsuccessfully for a suitable mailing list more suited to
> >>> my problem.
> >>>
> >>> Thank you for any pointers.
> >>>
> >>> Best regards,
> >>> Carlyle

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