+++ /dev/null
-.\" Copyright 1991 The Regents of the University of California.
-.\" All rights reserved.
-.\"
-.\" %%%LICENSE_START(BSD_4_CLAUSE_UCB)
-.\" Redistribution and use in source and binary forms, with or without
-.\" modification, are permitted provided that the following conditions
-.\" are met:
-.\" 1. Redistributions of source code must retain the above copyright
-.\" notice, this list of conditions and the following disclaimer.
-.\" 2. Redistributions in binary form must reproduce the above copyright
-.\" notice, this list of conditions and the following disclaimer in the
-.\" documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\" must display the following acknowledgement:
-.\" This product includes software developed by the University of
-.\" California, Berkeley and its contributors.
-.\" 4. 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
-.\"
-.\" @(#)popen.3 6.4 (Berkeley) 4/30/91
-.\"
-.\" Converted for Linux, Mon Nov 29 14:45:38 1993, faith@cs.unc.edu
-.\" Modified Sat May 18 20:37:44 1996 by Martin Schulze (joey@linux.de)
-.\" Modified 7 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
-.\"
-.TH POPEN 3 2013-04-19 "GNU" "Linux Programmer's Manual"
-.SH NAME
-popen, pclose \- pipe stream to or from a process
-.SH SYNOPSIS
-.nf
-.B #include <stdio.h>
-.sp
-.BI "FILE *popen(const char *" command ", const char *" type );
-.sp
-.BI "int pclose(FILE *" stream );
-.fi
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.ad l
-.in
-.sp
-.BR popen (),
-.BR pclose ():
-.RS 4
-_POSIX_C_SOURCE\ >=\ 2 || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE
-.RE
-.ad b
-.SH DESCRIPTION
-The
-.BR popen ()
-function opens a process by creating a pipe, forking, and invoking the
-shell.
-Since a pipe is by definition unidirectional, the
-.I type
-argument may specify only reading or writing, not both; the resulting
-stream is correspondingly read-only or write-only.
-.PP
-The
-.I command
-argument is a pointer to a null-terminated string containing a shell
-command line.
-This command is passed to
-.I /bin/sh
-using the
-.B \-c
-flag; interpretation, if any, is performed by the shell.
-The
-.I type
-argument is a pointer to a null-terminated string which must contain
-either the letter \(aqr\(aq for reading or the letter \(aqw\(aq for writing.
-Since glibc 2.9,
-this argument can additionally include the letter \(aqe\(aq,
-which causes the close-on-exec flag
-.RB ( FD_CLOEXEC )
-to be set on the underlying file descriptor;
-see the description of the
-.B O_CLOEXEC
-flag in
-.BR open (2)
-for reasons why this may be useful.
-.PP
-The return value from
-.BR popen ()
-is a normal standard I/O stream in all respects save that it must be closed
-with
-.BR pclose ()
-rather than
-.BR fclose (3).
-Writing to such a stream writes to the standard input of the command; the
-command's standard output is the same as that of the process that called
-.BR popen (),
-unless this is altered by the command itself.
-Conversely, reading from
-the stream reads the command's standard output, and the command's
-standard input is the same as that of the process that called
-.BR popen ().
-.PP
-Note that output
-.BR popen ()
-streams are fully buffered by default.
-.PP
-The
-.BR pclose ()
-function waits for the associated process to terminate and returns the exit
-status of the command as returned by
-.BR wait4 (2).
-.SH RETURN VALUE
-The
-.BR popen ()
-function returns NULL if the
-.BR fork (2)
-or
-.BR pipe (2)
-calls fail, or if it cannot allocate memory.
-.PP
-The
-.BR pclose ()
-function returns \-1 if
-.\" These conditions actually give undefined results, so I commented
-.\" them out.
-.\" .I stream
-.\" is not associated with a "popen()ed" command, if
-.\".I stream
-.\" already "pclose()d", or if
-.BR wait4 (2)
-returns an error, or some other error is detected.
-In the event of an error, these functions set
-.I errno
-to indicate the cause of the error.
-.SH ERRORS
-The
-.BR popen ()
-function does not set
-.I errno
-if memory allocation fails.
-If the underlying
-.BR fork (2)
-or
-.BR pipe (2)
-fails,
-.I errno
-is set appropriately.
-If the
-.I type
-argument is invalid, and this condition is detected,
-.I errno
-is set to
-.BR EINVAL .
-.PP
-If
-.BR pclose ()
-cannot obtain the child status,
-.I errno
-is set to
-.BR ECHILD .
-.SH CONFORMING TO
-POSIX.1-2001.
-
-The \(aqe\(aq value for
-.I type
-is a Linux extension.
-.SH BUGS
-Since the standard input of a command opened for reading shares its seek
-offset with the process that called
-.BR popen (),
-if the original process has done a buffered read, the command's input
-position may not be as expected.
-Similarly, the output from a command
-opened for writing may become intermingled with that of the original
-process.
-The latter can be avoided by calling
-.BR fflush (3)
-before
-.BR popen ().
-.PP
-Failure to execute the shell is indistinguishable from the shell's failure
-to execute command, or an immediate exit of the command.
-The only hint is an exit status of 127.
-.\" .SH HISTORY
-.\" A
-.\" .BR popen ()
-.\" and a
-.\" .BR pclose ()
-.\" function appeared in Version 7 AT&T UNIX.
-.SH SEE ALSO
-.BR sh (1),
-.BR fork (2),
-.BR pipe (2),
-.BR wait4 (2),
-.BR fclose (3),
-.BR fflush (3),
-.BR fopen (3),
-.BR stdio (3),
-.BR system (3)
-.SH COLOPHON
-This page is part of release 3.79 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
-\%http://www.kernel.org/doc/man\-pages/.
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