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)