[thirdparty/man-pages.git] / man3 / openpty.3

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.\" Converted into a manpage again by Martin Schulze <joey@infodrom.org>
.\"
.\" Added -lutil remark, 030718
.\"
.TH OPENPTY 3  "2003-07-18" "BSD" "Linux Programmer's Manual"
.SH NAME
openpty, login_tty, forkpty \- tty utility functions
.SH SYNOPSIS
.B #include <pty.h>
\ /* for openpty and forkpty */
.br
.B #include <utmp.h>
/* for login_tty */
.sp
.BI "int openpty(int *" amaster ", int *" aslave ", char *" name ", struct termios *" termp ", struct winsize * " winp );
.sp
.BI "int login_tty(int " fd );
.sp
.BI "pid_t forkpty(int *" amaster ", char *" name ", struct termios *" termp ", struct winsize *" winp );
.sp
Link with -lutil.
.SH DESCRIPTION
The
.B openpty()
function finds an available pseudo-tty 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 .

The
.B login_tty()
function prepares for a login on the tty
.I fd
(which may be a real tty device, or the slave of a pseudo-tty as
returned by
.BR openpty() )
by creating a new session, making
.I fd
the controlling terminal for the current process, setting
.I fd
to be the standard input, output, and error streams of the current
process, and closing
.IR fd .

The
.B forkpty()
function combines
.BR openpty() ,
.BR fork() ,
and
.B login_tty()
to create a new process operating in a pseudo-tty.  The file
descriptor of the master side of the pseudo-tty is returned in
.IR amaster ,
and the filename of the slave in
.I name
if it is not NULL.  The
.I termp
and
.I winp
parameters, if not NULL,
will determine the terminal attributes and window size of the slave
side of the pseudo-tty.
.SH "RETURN VALUES"
If a call to
.BR openpty() ,
.BR login_tty() ,
or
.B 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
.B forkpty()
return 0, and the parent process of
.B forkpty()
returns the process ID of the child process.
.SH ERRORS
.B openpty()
will fail if:
.TP
.B ENOENT
There are no available ttys.
.LP
.B login_pty()
will fail if
.B ioctl()
fails to set
.I fd
to the controlling terminal of the current process.
.LP
.B forkpty()
will fail if either
.B openpty()
or
.B fork()
fails.
.SH NOTE
These functions are included in libutil, hence you'll need to add
.B \-lutil
to your compiler commandline.
.SH FILES
.I /dev/[pt]ty[pqrstuwxyzabcdePQRST][0123456789abcdef]
.SH "CONFORMING TO"
These are BSD functions, present in libc5 and glibc2.
.SH BUGS
Nobody knows how much space should be reserved for
.IR name .
So, calling
.B openpty()
or
.B forkpty()
with non-NULL
.I name
may not be secure.
.SH "SEE ALSO"
.BR fork (2)
Commit	Line	Data
fea681da MK	1	.\" Copyright (c) OpenBSD Group
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. Neither the name of the University nor the names of its contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
	28	.\" Converted into a manpage again by Martin Schulze <joey@infodrom.org>
	29	.\"
	30	.\" Added -lutil remark, 030718
	31	.\"
	32	.TH OPENPTY 3 "2003-07-18" "BSD" "Linux Programmer's Manual"
	33	.SH NAME
	34	openpty, login_tty, forkpty \- tty utility functions
	35	.SH SYNOPSIS
	36	.B #include <pty.h>
	37	\ /* for openpty and forkpty */
	38	.br
	39	.B #include <utmp.h>
	40	/* for login_tty */
	41	.sp
	42	.BI "int openpty(int " amaster ", int " aslave ", char " name ", struct termios " termp ", struct winsize * " winp );
	43	.sp
	44	.BI "int login_tty(int " fd );
	45	.sp
	46	.BI "pid_t forkpty(int " amaster ", char " name ", struct termios " termp ", struct winsize " winp );
	47	.sp
	48	Link with -lutil.
	49	.SH DESCRIPTION
	50	The
	51	.B openpty()
	52	function finds an available pseudo-tty and returns file descriptors
	53	for the master and slave in
	54	.I amaster
	55	and
	56	.IR aslave .
	57	If
	58	.I name
	59	is not NULL, the filename of the slave is returned in
	60	.IR name .
	61	If
	62	.I termp
	63	is not NULL, the terminal parameters of the slave will be set to the
	64	values in
65	.IR termp .
66	If
67	.I winp
68	is not NULL, the window size of the slave will be set to the values in
69	.IR winp .
70
71	The
72	.B login_tty()
73	function prepares for a login on the tty
74	.I fd
75	(which may be a real tty device, or the slave of a pseudo-tty as
76	returned by
77	.BR openpty() )
78	by creating a new session, making
79	.I fd
80	the controlling terminal for the current process, setting
81	.I fd
82	to be the standard input, output, and error streams of the current
83	process, and closing
84	.IR fd .
85
86	The
87	.B forkpty()
88	function combines
89	.BR openpty() ,
90	.BR fork() ,
91	and
92	.B login_tty()
93	to create a new process operating in a pseudo-tty. The file
94	descriptor of the master side of the pseudo-tty is returned in
95	.IR amaster ,
96	and the filename of the slave in
97	.I name
98	if it is not NULL. The
99	.I termp
100	and
101	.I winp
102	parameters, if not NULL,
103	will determine the terminal attributes and window size of the slave
104	side of the pseudo-tty.
105	.SH "RETURN VALUES"
106	If a call to
107	.BR openpty() ,
108	.BR login_tty() ,
109	or
110	.B forkpty()
8729177b	111	is not successful, \-1 is returned and
fea681da MK	112	.I errno
	113	is set to indicate the error. Otherwise,
	114	.BR openpty() ,
	115	.BR login_tty() ,
	116	and the child process of
	117	.B forkpty()
	118	return 0, and the parent process of
	119	.B forkpty()
	120	returns the process ID of the child process.
	121	.SH ERRORS
	122	.B openpty()
	123	will fail if:
	124	.TP
	125	.B ENOENT
	126	There are no available ttys.
	127	.LP
	128	.B login_pty()
	129	will fail if
	130	.B ioctl()
	131	fails to set
	132	.I fd
	133	to the controlling terminal of the current process.
	134	.LP
	135	.B forkpty()
	136	will fail if either
	137	.B openpty()
	138	or
	139	.B fork()
	140	fails.
	141	.SH NOTE
	142	These functions are included in libutil, hence you'll need to add
	143	.B \-lutil
	144	to your compiler commandline.
	145	.SH FILES
	146	.I /dev/[pt]ty[pqrstuwxyzabcdePQRST][0123456789abcdef]
	147	.SH "CONFORMING TO"
	148	These are BSD functions, present in libc5 and glibc2.
	149	.SH BUGS
	150	Nobody knows how much space should be reserved for
	151	.IR name .
	152	So, calling
	153	.B openpty()
	154	or
	155	.B forkpty()
	156	with non-NULL
	157	.I name
	158	may not be secure.
	159	.SH "SEE ALSO"
	160	.BR fork (2)