ptsname(3)

NAME
ptsname, ptsname_r - get the name of the slave pseudoterminal

LIBRARY
Standard C library (libc, -lc)

SYNOPSIS
#include <stdlib.h>

char *ptsname(int fd);
int ptsname_r(size_t size;
              int fd, char buf[size], size_t size);

    Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

ptsname():
    Since glibc 2.24:
        _XOPEN_SOURCE >= 500
    glibc 2.23 and earlier:
        _XOPEN_SOURCE

ptsname_r():
    _GNU_SOURCE

DESCRIPTION
The ptsname() function returns the name of the slave pseudoterminal device corresponding to the master referred to by the file descriptor 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 size 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, an error number is returned to indicate the error.

ERRORS

EINVAL
    (ptsname_r() only) buf is NULL. (This error is returned only for glibc 2.25 and earlier.)

ENOTTY
    fd does not refer to a pseudoterminal master device.

ERANGE
    (ptsname_r() only) buf is too small.

ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value
 | Thread safety | MT-Unsafe race:ptsname
 | Thread safety | MT-Safe

VERSIONS
A version of ptsname_r() is documented on Tru64, HP-UX, and FreeBSD, but on those implementations, -1 is returned on error, with errno set to indicate the error. Avoid using this function in portable programs.

STANDARDS

ptsname():
    POSIX.1-2008.

ptsname_r():
    POSIX.1-2024.

HISTORY

ptsname():
    POSIX.1-2001. glibc 2.1.

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

ptsname_r():
    GNU.

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