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.Dd February 5, 2022
.Dt GRANTPT 3C
.Os
.Sh NAME
.Nm grantpt
.Nd grant access to the subsidiary device of a pseudo-terminal
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fo grantpt
.Fa "int fildes"
.Fc
.Sh DESCRIPTION
The
.Fn grantpt
function changes the mode and ownership of the pseudo-terminal subsidiary
device associated with its pseudo-terminal manager counterpart.
.Pp
The
.Fa fildes
argument is the file descriptor returned from a successful
.Xr open 2
of the pseudo-terminal manager device; e.g., by calling
.Xr posix_openpt 3C
or by performing an
.Xr open 2
of the
.Xr ptm 4D
device.
.Pp
The user ID owner of the subsidiary device is set to the real user ID of the
calling process.
The group ID owner is set to a reserved group.
.Pp
The permission mode of the subsidiary device is set to be readable and writable
by the owner, and writable by the group.
.Sh RETURN VALUES
.Rv -std grantpt
.Sh EXAMPLES
See
.Xr posix_openpt 3C
for an example that includes a call to
.Fn grantpt .
.Sh ERRORS
The
.Fn grantpt
function may fail if:
.Bl -tag -width Er
.It Er EBADF
The
.Fa fildes
argument is not a valid open file descriptor.
.It Er EINVAL
The
.Fa fildes
argument is not associated with a pseudo-terminal manager device.
.It Er EACCES
The corresponding pseudo-terminal subsidiary device could not be accessed.
.El
.Sh INTERFACE STABILITY
.Sy Committed
.Sh MT LEVEL
.Sy Safe
.Sh SEE ALSO
.Xr open 2 ,
.Xr posix_openpt 3C ,
.Xr ptsname 3C ,
.Xr unlockpt 3C ,
.Xr ptm 4D ,
.Xr attributes 7 ,
.Xr standards 7