NAME

       grantpt - grant access to the slave pseudoterminal

LIBRARY

       Standard C library (libc, -lc)

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
           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 to indicate
       the error.

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.

ATTRIBUTES

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

       ┌────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │Interface                                               │ Attribute     │ Value          │
       ├────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │grantpt()                                               │ Thread safety │ MT-Safe locale │
       └────────────────────────────────────────────────────────┴───────────────┴────────────────┘

STANDARDS

       POSIX.1-2008.

HISTORY

       glibc 2.1.  POSIX.1-2001.

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

       Historical systems implemented this  function  via  a  set-user-ID  helper  binary  called
       "pt_chown".   glibc  on  Linux  before glibc 2.33 could do so as well, in order to support
       configurations with only BSD pseudoterminals; this support has been  removed.   On  modern
       systems  this  is either a no-op —with permissions configured on pty allocation, as is the
       case on Linux— or an ioctl(2).

SEE ALSO

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