posix.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.ie \nF \{\
.    de IX
.    tm Index:\\$1\t\\n%\t"\\$2"
..
.    nr % 0
.    rr F
.\}
.el \{\
.    de IX
..
.\}
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "POSIX 3"
.TH POSIX 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
POSIX \- Perl interface to IEEE Std 1003.1
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&    use POSIX;
\&    use POSIX qw(setsid);
\&    use POSIX qw(:errno_h :fcntl_h);
\&
\&    printf "EINTR is %d\en", EINTR;
\&
\&    $sess_id = POSIX::setsid();
\&
\&    $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644);
\&        # note: that\*(Aqs a filedescriptor, *NOT* a filehandle
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \s-1POSIX\s0 module permits you to access all (or nearly all) the standard
\&\s-1POSIX\s0 1003.1 identifiers.  Many of these identifiers have been given Perl-ish
interfaces.
.PP
\&\fIEverything is exported by default\fR with the exception of any \s-1POSIX\s0
functions with the same name as a built-in Perl function, such as
\&\f(CW\*(C`abs\*(C'\fR, \f(CW\*(C`alarm\*(C'\fR, \f(CW\*(C`rmdir\*(C'\fR, \f(CW\*(C`write\*(C'\fR, etc.., which will be exported
only if you ask for them explicitly.  This is an unfortunate backwards
compatibility feature.  You can stop the exporting by saying \f(CW\*(C`use
POSIX ()\*(C'\fR and then use the fully qualified names (ie. \f(CW\*(C`POSIX::SEEK_END\*(C'\fR).
.PP
This document gives a condensed list of the features available in the \s-1POSIX\s0
module.  Consult your operating system's manpages for general information on
most features.  Consult perlfunc for functions which are noted as being
identical to Perl's builtin functions.
.PP
The first section describes \s-1POSIX\s0 functions from the 1003.1 specification.
The second section describes some classes for signal objects, \s-1TTY\s0 objects,
and other miscellaneous objects.  The remaining sections list various
constants and macros in an organization which roughly follows \s-1IEEE\s0 Std
1003.1b\-1993.
.SH "NOTE"
.IX Header "NOTE"
The \s-1POSIX\s0 module is probably the most complex Perl module supplied with
the standard distribution.  It incorporates autoloading, namespace games,
and dynamic loading of code that's in Perl, C, or both.  It's a great
source of wisdom.
.SH "CAVEATS"
.IX Header "CAVEATS"
A few functions are not implemented because they are C specific.  If you
attempt to call these, they will print a message telling you that they
aren't implemented, and suggest using the Perl equivalent should one
exist.  For example, trying to access the \fIsetjmp()\fR call will elicit the
message \*(L"\fIsetjmp()\fR is C\-specific: use eval {} instead\*(R".
.PP
Furthermore, some evil vendors will claim 1003.1 compliance, but in fact
are not so: they will not pass the \s-1PCTS\s0 (\s-1POSIX\s0 Compliance Test Suites).
For example, one vendor may not define \s-1EDEADLK\s0, or the semantics of the
errno values set by \fIopen\fR\|(2) might not be quite right.  Perl does not
attempt to verify \s-1POSIX\s0 compliance.  That means you can currently
successfully say \*(L"use \s-1POSIX\s0\*(R",  and then later in your program you find
that your vendor has been lax and there's no usable \s-1ICANON\s0 macro after
all.  This could be construed to be a bug.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.IP "_exit" 8
.IX Item "_exit"
This is identical to the C function \f(CW\*(C`_exit()\*(C'\fR.  It exits the program
immediately which means among other things buffered I/O is \fBnot\fR flushed.
.Sp
Note that when using threads and in Linux this is \fBnot\fR a good way to
exit a thread because in Linux processes and threads are kind of the
same thing (Note: while this is the situation in early 2003 there are
projects under way to have threads with more POSIXly semantics in Linux).
If you want not to return from a thread, detach the thread.
.IP "abort" 8
.IX Item "abort"
This is identical to the C function \f(CW\*(C`abort()\*(C'\fR.  It terminates the
process with a \f(CW\*(C`SIGABRT\*(C'\fR signal unless caught by a signal handler or
if the handler does not return normally (it e.g.  does a \f(CW\*(C`longjmp\*(C'\fR).
.IP "abs" 8
.IX Item "abs"
This is identical to Perl's builtin \f(CW\*(C`abs()\*(C'\fR function, returning
the absolute value of its numerical argument.
.IP "access" 8
.IX Item "access"
Determines the accessibility of a file.
.Sp
.Vb 3
\&        if( POSIX::access( "/", &POSIX::R_OK ) ){
\&                print "have read permission\en";
\&        }
.Ve
.Sp
Returns \f(CW\*(C`undef\*(C'\fR on failure.  Note: do not use \f(CW\*(C`access()\*(C'\fR for
security purposes.  Between the \f(CW\*(C`access()\*(C'\fR call and the operation
you are preparing for the permissions might change: a classic
\&\fIrace condition\fR.
.IP "acos" 8
.IX Item "acos"
This is identical to the C function \f(CW\*(C`acos()\*(C'\fR, returning
the arcus cosine of its numerical argument.  See also Math::Trig.
.IP "alarm" 8
.IX Item "alarm"
This is identical to Perl's builtin \f(CW\*(C`alarm()\*(C'\fR function,
either for arming or disarming the \f(CW\*(C`SIGARLM\*(C'\fR timer.
.IP "asctime" 8
.IX Item "asctime"
This is identical to the C function \f(CW\*(C`asctime()\*(C'\fR.  It returns
a string of the form
.Sp
.Vb 1
\&        "Fri Jun  2 18:22:13 2000\en\e0"
.Ve
.Sp
and it is called thusly
.Sp
.Vb 2
\&        $asctime = asctime($sec, $min, $hour, $mday, $mon, $year,
\&                           $wday, $yday, $isdst);
.Ve
.Sp
The \f(CW$mon\fR is zero-based: January equals \f(CW0\fR.  The \f(CW$year\fR is
1900\-based: 2001 equals \f(CW101\fR.  \f(CW$wday\fR and \f(CW$yday\fR default to zero
(and are usually ignored anyway), and \f(CW$isdst\fR defaults to \-1.
.IP "asin" 8
.IX Item "asin"
This is identical to the C function \f(CW\*(C`asin()\*(C'\fR, returning
the arcus sine of its numerical argument.  See also Math::Trig.
.IP "assert" 8
.IX Item "assert"
Unimplemented, but you can use \*(L"die\*(R" in perlfunc and the Carp module
to achieve similar things.
.IP "atan" 8
.IX Item "atan"
This is identical to the C function \f(CW\*(C`atan()\*(C'\fR, returning the
arcus tangent of its numerical argument.  See also Math::Trig.
.IP "atan2" 8
.IX Item "atan2"
This is identical to Perl's builtin \f(CW\*(C`atan2()\*(C'\fR function, returning
the arcus tangent defined by its two numerical arguments, the \fIy\fR
coordinate and the \fIx\fR coordinate.  See also Math::Trig.
.IP "atexit" 8
.IX Item "atexit"
\&\fIatexit()\fR is C\-specific: use \f(CW\*(C`END {}\*(C'\fR instead, see perlsub.
.IP "atof" 8
.IX Item "atof"
\&\fIatof()\fR is C\-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.
.IP "atoi" 8
.IX Item "atoi"
\&\fIatoi()\fR is C\-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.
If you need to have just the integer part, see \*(L"int\*(R" in perlfunc.
.IP "atol" 8
.IX Item "atol"
\&\fIatol()\fR is C\-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.
If you need to have just the integer part, see \*(L"int\*(R" in perlfunc.
.IP "bsearch" 8
.IX Item "bsearch"
\&\fIbsearch()\fR not supplied.  For doing binary search on wordlists,
see Search::Dict.
.IP "calloc" 8
.IX Item "calloc"
\&\fIcalloc()\fR is C\-specific.  Perl does memory management transparently.
.IP "ceil" 8
.IX Item "ceil"
This is identical to the C function \f(CW\*(C`ceil()\*(C'\fR, returning the smallest
integer value greater than or equal to the given numerical argument.
.IP "chdir" 8
.IX Item "chdir"
This is identical to Perl's builtin \f(CW\*(C`chdir()\*(C'\fR function, allowing
one to change the working (default) directory, see \*(L"chdir\*(R" in perlfunc.
.IP "chmod" 8
.IX Item "chmod"
This is identical to Perl's builtin \f(CW\*(C`chmod()\*(C'\fR function, allowing
one to change file and directory permissions, see \*(L"chmod\*(R" in perlfunc.
.IP "chown" 8
.IX Item "chown"
This is identical to Perl's builtin \f(CW\*(C`chown()\*(C'\fR function, allowing one
to change file and directory owners and groups, see \*(L"chown\*(R" in perlfunc.
.IP "clearerr" 8
.IX Item "clearerr"
Use the method \f(CW\*(C`IO::Handle::clearerr()\*(C'\fR instead, to reset the error
state (if any) and \s-1EOF\s0 state (if any) of the given stream.
.IP "clock" 8
.IX Item "clock"
This is identical to the C function \f(CW\*(C`clock()\*(C'\fR, returning the
amount of spent processor time in microseconds.
.IP "close" 8
.IX Item "close"
Close the file.  This uses file descriptors such as those obtained by calling
\&\f(CW\*(C`POSIX::open\*(C'\fR.
.Sp
.Vb 2
\&        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
\&        POSIX::close( $fd );
.Ve
.Sp
Returns \f(CW\*(C`undef\*(C'\fR on failure.
.Sp
See also \*(L"close\*(R" in perlfunc.
.IP "closedir" 8
.IX Item "closedir"
This is identical to Perl's builtin \f(CW\*(C`closedir()\*(C'\fR function for closing
a directory handle, see \*(L"closedir\*(R" in perlfunc.
.IP "cos" 8
.IX Item "cos"
This is identical to Perl's builtin \f(CW\*(C`cos()\*(C'\fR function, for returning
the cosine of its numerical argument, see \*(L"cos\*(R" in perlfunc.