ptsname man page

ptsname, ptsname_r — get the name of the slave pseudoterminal


#define _XOPEN_SOURCE /* See feature_test_macros(7) */

#include <stdlib.h>

char *ptsname(int fd);

#define _GNU_SOURCE /* See feature_test_macros(7) */

#include <stdlib.h>

int ptsname_r(int fd, char *buf, size_t buflen);


The ptsname() function returns the name of the slave pseudoterminal device corresponding to the master referred to by fd.

The ptsname_r() function is the reentrant equivalent of ptsname(). It returns the name of the slave pseudoterminal device as a null-terminated string in the buffer pointed to by buf. The buflen argument specifies the number of bytes available in buf.

Return Value

On success, ptsname() returns a pointer to a string in static storage which will be overwritten by subsequent calls. This pointer must not be freed. On failure, NULL is returned.

On success, ptsname_r() returns 0. On failure, a nonzero value is returned and errno is set to indicate the error.


(ptsname_r() only) buf is NULL.
fd does not refer to a pseudoterminal master device.
(ptsname_r() only) buf is too small.


ptsname() is provided in glibc since version 2.1.


For an explanation of the terms used in this section, see attributes(7).

ptsname()Thread safetyMT-Unsafe race:ptsname
ptsname_r()Thread safetyMT-Safe

Conforming to

POSIX.1-2001, POSIX.1-2008.

ptsname() is part of the UNIX 98 pseudoterminal support (see pts(4)).

ptsname_r() is a Linux extension, that is proposed for inclusion in the next major revision of POSIX.1 (Issue 8). A version of this function is documented on Tru64 and HP-UX, but on those implementations, -1 is returned on error, with errno set to indicate the error. Avoid using this function in portable programs.

See Also

grantpt(3), posix_openpt(3), ttyname(3), unlockpt(3), pts(4), pty(7)


This page is part of release 4.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By

getpt(3), grantpt(3), posix_openpt(3), pts(4), pty(7), unlockpt(3).

ptsname_r(3) is an alias of ptsname(3).

2016-12-12 Linux Programmer's Manual