ctermid(S)                     6 January 1993                     ctermid(S)


 Name

    ctermid - generate terminal filename

 Syntax


    cc  . . .  -lc


    #include  <stdio.h>

    char *ctermid (s)
    char *s;


 Description

    The ctermid function generates the path name of the controlling terminal
    for the current process and stores it in a string.

    If s is a NULL pointer, the string is stored in an internal static area,
    the contents of which are overwritten at the next call to ctermid, and
    the address of which is returned.  Otherwise, s is assumed to point to a
    character array of at least Lctermid elements; the path name is placed
    in this array, and the value of s is returned.  The constant Lctermid is
    defined in the <stdio.h> header file.

 Notes

    The difference between ctermid and ttyname(S) is that ttyname must be
    handed a file descriptor and returns the actual name of the terminal
    associated with that file descriptor, while ctermid returns a string
    (/dev/tty) that refers to the terminal if used as a file name.  Thus
    ttyname is useful only if the process already has at least one file open
    to a terminal.

 See also

    ttyname(S)

 Standards conformance

    ctermid is conformant with:
    AT&T SVID Issue 2;
    X/Open Portability Guide, Issue 3, 1989;
    IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C
    Language] (ISO/IEC 9945-1);
    and NIST FIPS 151-1.