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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" %%%LICENSE_END .\" .\" Converted into a manpage again by Martin Schulze .\" .\" Added -lutil remark, 030718 .\" .TH OPENPTY 3 2017-09-15 "GNU" "Linux Programmer's Manual" .SH NAME openpty, login_tty, forkpty \- terminal utility functions .SH SYNOPSIS .nf .B #include .PP .BI "int openpty(int *" amaster ", int *" aslave ", char *" name , .BI " const struct termios *" termp , .BI " const struct winsize *" winp ); .PP .BI "pid_t forkpty(int *" amaster ", char *" name , .BI " const struct termios *" termp , .BI " const struct winsize *" winp ); .B #include .PP .BI "int login_tty(int " fd ); .PP Link with \fI\-lutil\fP. .fi .SH DESCRIPTION The .BR openpty () function finds an available pseudoterminal and returns file descriptors for the master and slave in .I amaster and .IR aslave . If .I name is not NULL, the filename of the slave is returned in .IR name . If .I termp is not NULL, the terminal parameters of the slave will be set to the values in .IR termp . If .I winp is not NULL, the window size of the slave will be set to the values in .IR winp . .PP The .BR login_tty () function prepares for a login on the terminal referred to by the file descriptor .I fd (which may be a real terminal device, or the slave of a pseudoterminal as returned by .BR openpty ()) by creating a new session, making .I fd the controlling terminal for the calling process, setting .I fd to be the standard input, output, and error streams of the current process, and closing .IR fd . .PP The .BR forkpty () function combines .BR openpty (), .BR fork (2), and .BR login_tty () to create a new process operating in a pseudoterminal. A file descriptor referring to master side of the pseudoterminal is returned in .IR amaster . If .I name is not NULL, the buffer it points to is used to return the filename of the slave. The .I termp and .I winp arguments, if not NULL, will determine the terminal attributes and window size of the slave side of the pseudoterminal. .SH RETURN VALUE If a call to .BR openpty (), .BR login_tty (), or .BR forkpty () is not successful, \-1 is returned and .I errno is set to indicate the error. Otherwise, .BR openpty (), .BR login_tty (), and the child process of .BR forkpty () return 0, and the parent process of .BR forkpty () returns the process ID of the child process. .SH ERRORS .BR openpty () fails if: .TP .B ENOENT There are no available terminals. .PP .BR login_tty () fails if .BR ioctl (2) fails to set .I fd to the controlling terminal of the calling process. .PP .BR forkpty () fails if either .BR openpty () or .BR fork (2) fails. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbw20 lb lb l l l. Interface Attribute Value T{ .BR forkpty (), .BR openpty () T} Thread safety MT-Safe locale T{ .BR login_tty () T} Thread safety MT-Unsafe race:ttyname .TE .sp 1 .SH CONFORMING TO These are BSD functions, present in glibc. They are not standardized in POSIX. .SH NOTES The .B const modifiers were added to the structure pointer arguments of .BR openpty () and .BR forkpty () in glibc 2.8. .PP In versions of glibc before 2.0.92, .BR openpty () returns file descriptors for a BSD pseudoterminal pair; since glibc 2.0.92, it first attempts to open a UNIX 98 pseudoterminal pair, and falls back to opening a BSD pseudoterminal pair if that fails. .SH BUGS Nobody knows how much space should be reserved for .IR name . So, calling .BR openpty () or .BR forkpty () with non-NULL .I name may not be secure. .SH SEE ALSO .BR fork (2), .BR ttyname (3), .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/.