ctermid_r(3S) — DG/UX R4.11MU05



ctermid(3S)                    DG/UX R4.11MU05                   ctermid(3S)


NAME
       ctermid, ctermidr - generate file name for terminal

SYNOPSIS
       #include <stdio.h>
       char *ctermid(char *s);
       char *ctermidr(char *s);

DESCRIPTION
       ctermid and ctermidr generate the path name of the controlling
       terminal for the current process, and store it in a string.

       If s is a NULL pointer, ctermid stores the string in an internal
       static area, the contents of which are overwritten at the next call
       to ctermid, and the address of which is returned.  If s is a NULL
       pointer, ctermidr returns a NULL pointer.  Otherwise, both functions
       assume s points 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.


   Considerations for Threads Programming
                     +----------+-----------------------------+
                     |          |                      async- |
                     |function  | reentrant   cancel   cancel |
                     |          |             point     safe  |
                     +----------+-----------------------------+
                     |ctermid   |     N         -        -    |
                     |ctermidr |     Y         N        N    |
                     +----------+-----------------------------+

REFERENCES
       reentrant(3), ttyname(3C).

NOTES
       The function ctermidr is only available in the shared library,
       libc.so.

       The difference between ctermid and ttyname(3C) as well as ctermidr
       and ttynamer is that the ttyname functions must be handed a file
       descriptor and return the actual name of the terminal associated with
       that file descriptor, while ctermid functions return a string
       (/dev/tty) that will refer to the terminal if used as a file name.
       Thus the ttyname functions are useful only if the process already has
       at least one file open to a terminal.


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