ctermid(3)		    Library Functions Manual		      ctermid(3)

NAME
     ctermid - get controlling terminal name

LIBRARY
     Standard C library (libc, -lc)

SYNOPSIS
     #include <stdio.h>

     char *ctermid(char *s);

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

     ctermid():
	 _POSIX_C_SOURCE

DESCRIPTION
     ctermid()	returns	 a string which is the pathname for the current control-
     ling 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  re-
     turned pathname.

RETURN VALUE
     The pointer to the pathname.

ATTRIBUTES
     For  an  explanation  of the terms used in this section, see attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ ctermid()
     T}	  Thread safety	  MT-Safe

STANDARDS
     POSIX.1-2008.

HISTORY
     POSIX.1-2001, Svr4.

BUGS
     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
     ttyname(3)

Linux man-pages 6.18		   2026-02-08			      ctermid(3)