ptyget.8

.TH ptyget 8
.SH NAME
ptyget \- allocate a pty
.SH SYNOPSIS
.B ptyget
.I subprogram
[
.I args ...
]
.SH DESCRIPTION
.B ptyget
allocates a new pty,
makes the master side available as fd 4 (non-blocking),
makes the slave side available as fd 5,
and runs
.IR subprogram .
It passes
.I subprogram
a TTY environment variable
giving the name of the pty slave.

On current systems,
.B ptyget
is setuid root and setgid tty.
It changes the ownership of the pty slave to the user,
so that the user can open it,
and makes it mode 600,
so that nobody else can open it.
It also puts the pty slave under group tty.
It will refuse to run if these protections fail.

.B ptyget
does not make any provisions to clean up when the
user finishes using the pty.
.SH "SYSTEM-SPECIFIC NOTES"
On pty/tty-based systems (e.g., BSD 4.4),
the slave is
.B /dev/tty\fIxy
where
.I xy
are two characters.
.B ptyget
searches through masters starting from a random point
(with a random increment to avoid secondary clustering).
.B ptyget
relies for security on the kernel's
.B revoke()
function.

On ptmx/pts-based systems (e.g., Solaris),
the slave is 
.B /dev/pts/\fIN
where
.I N
is a nonnegative integer.
.B ptyget
does not invoke
.BR /usr/lib/pt_chmod .
.B ptyget
relies for security on the kernel's built-in slave locking.
.SH "SEE ALSO"
ptyget(8)