HP-UX Reference (11i v3 07/02) - 3 Library Functions A-M (vol 6)

ctermid(3S) ctermid(3S)

NAME

ctermid() - generate ﬁle name for terminal

SYNOPSIS

#include <stdio.h>

char *ctermid(char *s);

DESCRIPTION

ctermid() generates a string that, when used as a pathname, refers to the controlling terminal for the

current process.

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

L_ctermid elements; the path name is placed in this array and the value of

s is returned. The constant

L_ctermid is deﬁned in the

<stdio.h> header ﬁle.

If the process has no controlling terminal, the pathname for the controlling terminal cannot be determined,

or some other error occurs,

ctermid() returns an empty string.

For multi-thread applications, if s is a NULL pointer, the operation is not performed and a NULL pointer is

returned.

Notes

The difference between

ctermid() and ttyname() is that ttyname() must be handed a ﬁle descrip-

tor 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. (see ttyname(3C)). Thus

ttyname() is useful only if the process already has at least one ﬁle open to a terminal.