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 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.
APPLICATION USAGE
ctermid()
is thread-safe. It is not async-cancel-safe.
NOTES
The difference between
ctermid()
and
ttyname()
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.
(see
ttyname(3C)).
Thus
ttyname()
is useful only if the process already has at least one file open
to a terminal.
STANDARDS CONFORMANCE
ctermid(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
