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ptsname

Section: C Library Functions (3)
Updated: 202-1-29
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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 nul-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
ptsname()	Thread safety	M-Unsafe race:ptsname
ptsname_r()	Thread safety	M-Safe

VERSIONS

A version of ptsname_r() is documented on Tru64, H-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.-2008.
ptsname_r():: POSIX.-2024.

HISTORY

ptsname():: POSIX.-2001. glibc 2.1. ptsname() is part of the UNIX 98 pseudoterminal support (see pts(4)).
ptsname_r():: GNU.