mirror of https://github.com/mkerrisk/man-pages
173 lines
4.6 KiB
Groff
173 lines
4.6 KiB
Groff
.\" Copyright (c) OpenBSD Group
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" Converted into a manpage again by Martin Schulze <joey@infodrom.org>
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.\"
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.\" Added -lutil remark, 030718
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.\"
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.TH OPENPTY 3 2003-07-18 "GNU" "Linux Programmer's Manual"
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.SH NAME
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openpty, login_tty, forkpty \- tty utility functions
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.SH SYNOPSIS
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.nf
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.B #include <pty.h>
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.sp
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.BI "int openpty(int *" amaster ", int *" aslave ", char *" name ,
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.BI " struct termios *" termp ", struct winsize *" winp );
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.sp
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.BI "pid_t forkpty(int *" amaster ", char *" name ", struct termios *" termp ,
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.BI " struct winsize *" winp );
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.sp
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.B #include <utmp.h>
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.sp
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.BI "int login_tty(int " fd );
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.sp
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Link with \fI\-lutil\fP.
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.fi
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.SH DESCRIPTION
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The
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.BR openpty ()
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function finds an available pseudo-terminal and returns file descriptors
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for the master and slave in
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.I amaster
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and
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.IR aslave .
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If
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.I name
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is not NULL, the filename of the slave is returned in
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.IR name .
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If
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.I termp
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is not NULL, the terminal parameters of the slave will be set to the
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values in
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.IR termp .
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If
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.I winp
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is not NULL, the window size of the slave will be set to the values in
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.IR winp .
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The
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.BR login_tty ()
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function prepares for a login on the tty
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.I fd
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(which may be a real tty device, or the slave of a pseudo-terminal as
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returned by
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.BR openpty ())
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by creating a new session, making
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.I fd
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the controlling terminal for the calling process, setting
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.I fd
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to be the standard input, output, and error streams of the current
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process, and closing
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.IR fd .
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The
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.BR forkpty ()
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function combines
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.BR openpty (),
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.BR fork (2),
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and
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.BR login_tty ()
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to create a new process operating in a pseudo-terminal.
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The file
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descriptor of the master side of the pseudo-terminal is returned in
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.IR amaster ,
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and the filename of the slave in
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.I name
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if it is not NULL.
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The
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.I termp
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and
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.I winp
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parameters, if not NULL,
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will determine the terminal attributes and window size of the slave
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side of the pseudo-terminal.
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.SH "RETURN VALUE"
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If a call to
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.BR openpty (),
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.BR login_tty (),
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or
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.BR forkpty ()
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is not successful, \-1 is returned and
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.I errno
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is set to indicate the error.
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Otherwise,
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.BR openpty (),
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.BR login_tty (),
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and the child process of
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.BR forkpty ()
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return 0, and the parent process of
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.BR forkpty ()
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returns the process ID of the child process.
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.SH ERRORS
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.BR openpty ()
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will fail if:
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.TP
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.B ENOENT
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There are no available ttys.
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.LP
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.BR login_tty ()
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will fail if
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.BR ioctl (2)
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fails to set
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.I fd
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to the controlling terminal of the calling process.
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.LP
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.BR forkpty ()
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will fail if either
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.BR openpty ()
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or
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.BR fork (2)
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fails.
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.SH "CONFORMING TO"
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These are BSD functions, present in libc5 and glibc2.
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.SH NOTES
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.\" These functions are included in libutil, hence you'll need to add
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.\" .B \-lutil
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.\" to your compiler command line.
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.\"
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In versions of glibc before 2.0.92,
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.BR openpty ()
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returns file descriptors for a BSD pseudo-terminal pair;
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since glibc 2.0.92,
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it first attempts to open a Unix 98 pseudo-terminal pair,
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and falls back to opening a BSD pseudo-terminal pair if that fails.
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.SH BUGS
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Nobody knows how much space should be reserved for
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.IR name .
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So, calling
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.BR openpty ()
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or
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.BR forkpty ()
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with non-NULL
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.I name
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may not be secure.
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.SH "SEE ALSO"
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.BR fork (2),
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.BR ttyname (3),
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.BR pty (7)
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