Section (3) grantpt
grantpt — grant access to the slave pseudoterminal
changes the mode and owner of the slave pseudoterminal device
corresponding to the master pseudoterminal referred to by
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
The behavior of
unspecified if a signal handler is installed to catch
returns 0. Otherwise, it returns −1 and sets
The corresponding slave pseudoterminal could not be accessed.
fdargument is not a valid open file descriptor.
fdargument is valid but not associated with a master pseudoterminal.
For an explanation of the terms used in this section, see attributes(7).
||Thread safety||MT-Safe locale|
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).
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