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ptsname

Section: C Library Functions (3)
Updated: 2023-02-05
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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(int fd, char buf[.buflen], size_t buflen);

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 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, 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.
 

VERSIONS

ptsname() is provided since glibc 2.1.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
ptsname() Thread safetyMT-Unsafe race:ptsname
ptsname_r() Thread safetyMT-Safe

 

STANDARDS

ptsname():
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)

 

Index

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
ATTRIBUTES
STANDARDS
SEE ALSO
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Time: 11:39:50 GMT, September 14, 2026