.\" %%%LICENSE_START(PUBLIC_DOMAIN) .\" This page is in the public domain. - aeb .\" %%%LICENSE_END .\" .TH GRANTPT 3 2017-09-15 "GNU" "Linux Programmer's Manual" .SH NAME grantpt \- grant access to the slave pseudoterminal .SH SYNOPSIS .B #include .PP .BI "int grantpt(int " fd ");" .PP .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .PP .ad l .BR grantpt (): .br .RS 4 Since glibc 2.24: _XOPEN_SOURCE\ >=\ 500 || (_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) .br Glibc 2.23 and earlier: _XOPEN_SOURCE .RE .ad .SH DESCRIPTION The .BR grantpt () function changes the mode and owner of the slave pseudoterminal device corresponding to the master pseudoterminal referred to by the file descriptor .IR 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., .IR tty ). The mode of the slave is set to 0620 (crw\-\-w\-\-\-\-). .PP The behavior of .BR grantpt () is unspecified if a signal handler is installed to catch .B SIGCHLD signals. .SH RETURN VALUE When successful, .BR grantpt () returns 0. Otherwise, it returns \-1 and sets .I errno appropriately. .SH ERRORS .TP .B EACCES The corresponding slave pseudoterminal could not be accessed. .TP .B EBADF The .I fd argument is not a valid open file descriptor. .TP .B EINVAL The .I fd argument is valid but not associated with a master pseudoterminal. .SH VERSIONS .BR grantpt () is provided in glibc since version 2.1. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lb lb lb l l l. Interface Attribute Value T{ .BR grantpt () T} Thread safety MT-Safe locale .TE .sp 1 .SH CONFORMING TO POSIX.1-2001, POSIX.1-2008. .SH NOTES This is part of the UNIX 98 pseudoterminal support, see .BR pts (4). .PP 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 .RB ( posix_openpt (3)), so that nothing must be done by .BR 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). .SH SEE ALSO .BR open (2), .BR posix_openpt (3), .BR ptsname (3), .BR unlockpt (3), .BR pts (4), .BR pty (7) .SH COLOPHON This page is part of release 5.10 of the Linux .I man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at \%https://www.kernel.org/doc/man\-pages/.