NAME

       grantpt - grant access to the slave pseudoterminal

SYNOPSIS

       #include <stdlib.h>

       int grantpt(int fd);

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

       grantpt():
           Since glibc 2.24:
               _XOPEN_SOURCE >= 500 ||
                   (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
           Glibc 2.23 and earlier:
               _XOPEN_SOURCE

DESCRIPTION

       The grantpt() function changes the mode and owner of the slave pseudoterminal device corresponding to the
       master pseudoterminal referred to by the file descriptor fd.  The user ID of the slave is set to the real
       UID  of  the  calling process.  The group ID is set to an unspecified value (e.g., tty).  The mode of the
       slave is set to 0620 (crw--w----).

       The behavior of grantpt() is unspecified if a signal handler is installed to catch SIGCHLD signals.

RETURN VALUE

       When successful, grantpt() returns 0.  Otherwise, it returns -1 and sets errno appropriately.

ERRORS

       EACCES The corresponding slave pseudoterminal could not be accessed.

       EBADF  The fd argument is not a valid open file descriptor.

       EINVAL The fd argument is valid but not associated with a master pseudoterminal.

VERSIONS

       grantpt() is provided in glibc since version 2.1.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌───────────┬───────────────┬────────────────┐
       │ Interface │ Attribute     │ Value          │
       ├───────────┼───────────────┼────────────────┤
       │ grantpt() │ Thread safety │ MT-Safe locale │
       └───────────┴───────────────┴────────────────┘

CONFORMING TO

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

NOTES

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

       Many systems implement this function via a set-user-ID helper binary called "pt_chown".  On Linux systems
       with a devpts filesystem (present since Linux 2.2), the kernel normally sets the  correct  ownership  and
       permissions  for  the  pseudoterminal  slave when the master is opened (posix_openpt(3)), so that nothing
       must be done by grantpt().  Thus, no such helper binary is required (and indeed it is  configured  to  be
       absent during the glibc build that is typical on many systems).

SEE ALSO

       open(2), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)

COLOPHON

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       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.

GNU                                                2017-09-15                                         GRANTPT(3)