ctermid(3) — Linux manual page

ctermid(3)               Library Functions Manual              ctermid(3)

NAME         top

       ctermid - get controlling terminal name

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <stdio.h>

       char *ctermid(char *s);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       ctermid():
           _POSIX_C_SOURCE

DESCRIPTION         top

       ctermid() returns a string which is the pathname for the current
       controlling terminal for this process.  If s is NULL, a static
       buffer is used, otherwise s points to a buffer used to hold the
       terminal pathname.  The symbolic constant L_ctermid is the maximum
       number of characters in the returned pathname.

RETURN VALUE         top

       The pointer to the pathname.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ ctermid()                            │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       POSIX.1-2001, Svr4.

BUGS         top

       The returned pathname may not uniquely identify the controlling
       terminal; it may, for example, be /dev/tty.

       It is not assured that the program can open the terminal.

SEE ALSO         top

       ttyname(3)

COLOPHON         top

       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-6.15.tar.gz
       fetched from
       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
       2025-08-11.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to
       man-pages@man7.org

Linux man-pages 6.15            2025-05-17                     ctermid(3)

Pages that refer to this page: ttyname(3)

HTML rendering created 2025-09-06 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.