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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | BUGS | SEE ALSO | COLOPHON |
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openpty(3) Library Functions Manual openpty(3)
openpty, login_tty, forkpty - terminal utility functions
System utilities library (libutil, -lutil)
#include <pty.h>
int openpty(int *amaster, int *aslave, char *name,
const struct termios *termp,
const struct winsize *winp);
pid_t forkpty(int *amaster, char *name,
const struct termios *termp,
const struct winsize *winp);
#include <utmp.h>
int login_tty(int fd);
The openpty() function finds an available pseudoterminal and
returns file descriptors for the master and slave in amaster and
aslave. If name is not NULL, the filename of the slave is
returned in name. If termp is not NULL, the terminal parameters
of the slave will be set to the values in termp. If winp is not
NULL, the window size of the slave will be set to the values in
winp.
The login_tty() function prepares for a login on the terminal
referred to by the file descriptor fd (which may be a real
terminal device, or the slave of a pseudoterminal as returned by
openpty()) by creating a new session, making fd the controlling
terminal for the calling process, setting fd to be the standard
input, output, and error streams of the current process, and
closing fd.
The forkpty() function combines openpty(), fork(2), and
login_tty() to create a new process operating in a
pseudoterminal. A file descriptor referring to master side of
the pseudoterminal is returned in amaster. If name is not NULL,
the buffer it points to is used to return the filename of the
slave. The termp and winp arguments, if not NULL, will determine
the terminal attributes and window size of the slave side of the
pseudoterminal.
If a call to openpty(), login_tty(), or forkpty() is not
successful, -1 is returned and errno is set to indicate the
error. Otherwise, openpty(), login_tty(), and the child process
of forkpty() return 0, and the parent process of forkpty()
returns the process ID of the child process.
openpty() fails if:
ENOENT There are no available terminals.
login_tty() fails if ioctl(2) fails to set fd to the controlling
terminal of the calling process.
forkpty() fails if either openpty() or fork(2) fails.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────┬───────────────┬────────────────────────┐
│ Interface │ Attribute │ Value │
├──────────────────────┼───────────────┼────────────────────────┤
│ forkpty(), openpty() │ Thread safety │ MT-Safe locale │
├──────────────────────┼───────────────┼────────────────────────┤
│ login_tty() │ Thread safety │ MT-Unsafe race:ttyname │
└──────────────────────┴───────────────┴────────────────────────┘
BSD.
The const modifiers were added to the structure pointer arguments
of openpty() and forkpty() in glibc 2.8.
Before glibc 2.0.92, openpty() returns file descriptors for a BSD
pseudoterminal pair; since glibc 2.0.92, it first attempts to
open a UNIX 98 pseudoterminal pair, and falls back to opening a
BSD pseudoterminal pair if that fails.
Nobody knows how much space should be reserved for name. So,
calling openpty() or forkpty() with non-NULL name may not be
secure.
fork(2), ttyname(3), pty(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 openpty(3)
Pages that refer to this page: pty(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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