NAME
ptsname, ptsname_r
— get the pathname of the slave
pseudo-terminal device
LIBRARY
library “libc”
SYNOPSIS
#include
<stdlib.h>
char *
ptsname(int
masterfd);
int
ptsname_r(int
masterfd, char
*buf, size_t
buflen);
DESCRIPTION
Theptsname()
function returns the pathname of the slave pseudo-terminal device that
corresponds to the master pseudo-terminal device associated with
masterfd. The ptsname() function
is not reentrant or thread-safe.
The
ptsname_r()
function places the pathname of the slave pseudo-terminal device that
corresponds to the master pseudo-terminal device associated with
masterfd int the buf argument
copying up to buflen characters. The
buf is always NUL
terminated.
RETURN VALUES
If successful, ptsname() returns a pointer
to a nul-terminated string containing the pathname of the slave
pseudo-terminal device. If an error occurs ptsname()
will return NULL and errno is
set to indicate the error.
If successful, ptsname_r() places a
nul-terminated string containing the pathname of the slave pseudo-terminal
device in buf and returns 0.
If an error occurs ptsname_r() will return an error
number indicating what went wrong.
ERRORS
The ptsname() and
ptsname_r() functions will fail if:
- [
EACCESS] - the corresponding pseudo-terminal device could not be accessed.
- [
EBADF] - masterfd is not a valid descriptor.
- [
EINVAL] - masterfd is not associated with a master pseudo-terminal device.
In addition the ptsname_r() function will
return:
- [
EINVAL] - the buf argument is
NULL. - [
ERANGE] - the name of the pseudo-terminal is longer than
bufsiz characters plus the terminating
NUL.
NOTES
The error returns of
ptsname()
are a NetBSD extension. The
ptsname() function is equivalent to:
struct ptmget pm; return ioctl(masterfd, TIOCPTSNAME, &pm) == -1 ? NULL : pm.sn;
Both the
ptsname()
and ptsname_r() functions will also return the name
of the slave pseudo-terminal if a file descriptor to the slave
pseudo-terminal is passed to masterfd.
This is a convenient extension because it allows one to use the file descriptor obtained by open(2) /dev/tty to obtain the name of the pseudo-terminal for the current process.
SEE ALSO
STANDARDS
The ptsname() function conforms to
IEEE Std 1003.1-2001 (“POSIX.1”). Its
first release was in X/Open Portability Guide
Issue 4, Version 2 (“XPG4.2”).