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.

See also Math::Trig.
.IP "cosh" 8
.IX Item "cosh"
This is identical to the C function \f(CW\*(C`cosh()\*(C'\fR, for returning
the hyperbolic cosine of its numeric argument.  See also Math::Trig.
.IP "creat" 8
.IX Item "creat"
Create a new file.  This returns a file descriptor like the ones returned by
\&\f(CW\*(C`POSIX::open\*(C'\fR.  Use \f(CW\*(C`POSIX::close\*(C'\fR to close the file.
.Sp
.Vb 2
\&        $fd = POSIX::creat( "foo", 0611 );
\&        POSIX::close( $fd );
.Ve
.Sp
See also \*(L"sysopen\*(R" in perlfunc and its \f(CW\*(C`O_CREAT\*(C'\fR flag.
.IP "ctermid" 8
.IX Item "ctermid"
Generates the path name for the controlling terminal.
.Sp
.Vb 1
\&        $path = POSIX::ctermid();
.Ve
.IP "ctime" 8
.IX Item "ctime"
This is identical to the C function \f(CW\*(C`ctime()\*(C'\fR and equivalent
to \f(CW\*(C`asctime(localtime(...))\*(C'\fR, see \*(L"asctime\*(R" and \*(L"localtime\*(R".
.IP "cuserid" 8
.IX Item "cuserid"
Get the login name of the owner of the current process.
.Sp
.Vb 1
\&        $name = POSIX::cuserid();
.Ve
.IP "difftime" 8
.IX Item "difftime"
This is identical to the C function \f(CW\*(C`difftime()\*(C'\fR, for returning
the time difference (in seconds) between two times (as returned
by \f(CW\*(C`time()\*(C'\fR), see \*(L"time\*(R".
.IP "div" 8
.IX Item "div"
\&\fIdiv()\fR is C\-specific, use \*(L"int\*(R" in perlfunc on the usual \f(CW\*(C`/\*(C'\fR division and
the modulus \f(CW\*(C`%\*(C'\fR.
.IP "dup" 8
.IX Item "dup"
This is similar to the C function \f(CW\*(C`dup()\*(C'\fR, for duplicating a file
descriptor.
.Sp
This uses file descriptors such as those obtained by calling
\&\f(CW\*(C`POSIX::open\*(C'\fR.
.Sp
Returns \f(CW\*(C`undef\*(C'\fR on failure.
.IP "dup2" 8
.IX Item "dup2"
This is similar to the C function \f(CW\*(C`dup2()\*(C'\fR, for duplicating a file
descriptor to an another known file descriptor.
.Sp
This uses file descriptors such as those obtained by calling
\&\f(CW\*(C`POSIX::open\*(C'\fR.
.Sp
Returns \f(CW\*(C`undef\*(C'\fR on failure.
.IP "errno" 8
.IX Item "errno"
Returns the value of errno.
.Sp
.Vb 1
\&        $errno = POSIX::errno();
.Ve
.Sp
This identical to the numerical values of the \f(CW$!\fR, see \*(L"$ERRNO\*(R" in perlvar.
.IP "execl" 8
.IX Item "execl"
\&\fIexecl()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "execle" 8
.IX Item "execle"
\&\fIexecle()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "execlp" 8
.IX Item "execlp"
\&\fIexeclp()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "execv" 8
.IX Item "execv"
\&\fIexecv()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "execve" 8
.IX Item "execve"
\&\fIexecve()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "execvp" 8
.IX Item "execvp"
\&\fIexecvp()\fR is C\-specific, see \*(L"exec\*(R" in perlfunc.
.IP "exit" 8
.IX Item "exit"
This is identical to Perl's builtin \f(CW\*(C`exit()\*(C'\fR function for exiting the
program, see \*(L"exit\*(R" in perlfunc.
.IP "exp" 8
.IX Item "exp"
This is identical to Perl's builtin \f(CW\*(C`exp()\*(C'\fR function for
returning the exponent (\fIe\fR\-based) of the numerical argument,
see \*(L"exp\*(R" in perlfunc.
.IP "fabs" 8
.IX Item "fabs"
This is identical to Perl's builtin \f(CW\*(C`abs()\*(C'\fR function for returning
the absolute value of the numerical argument, see \*(L"abs\*(R" in perlfunc.
.IP "fclose" 8
.IX Item "fclose"
Use method \f(CW\*(C`IO::Handle::close()\*(C'\fR instead, or see \*(L"close\*(R" in perlfunc.
.IP "fcntl" 8
.IX Item "fcntl"
This is identical to Perl's builtin \f(CW\*(C`fcntl()\*(C'\fR function,
see \*(L"fcntl\*(R" in perlfunc.
.IP "fdopen" 8
.IX Item "fdopen"
Use method \f(CW\*(C`IO::Handle::new_from_fd()\*(C'\fR instead, or see \*(L"open\*(R" in perlfunc.
.IP "feof" 8
.IX Item "feof"
Use method \f(CW\*(C`IO::Handle::eof()\*(C'\fR instead, or see \*(L"eof\*(R" in perlfunc.
.IP "ferror" 8
.IX Item "ferror"
Use method \f(CW\*(C`IO::Handle::error()\*(C'\fR instead.
.IP "fflush" 8
.IX Item "fflush"
Use method \f(CW\*(C`IO::Handle::flush()\*(C'\fR instead.
See also \*(L"$OUTPUT_AUTOFLUSH\*(R" in perlvar.
.IP "fgetc" 8
.IX Item "fgetc"
Use method \f(CW\*(C`IO::Handle::getc()\*(C'\fR instead, or see \*(L"read\*(R" in perlfunc.
.IP "fgetpos" 8
.IX Item "fgetpos"
Use method \f(CW\*(C`IO::Seekable::getpos()\*(C'\fR instead, or see \*(L"seek\*(R" in L.
.IP "fgets" 8
.IX Item "fgets"
Use method \f(CW\*(C`IO::Handle::gets()\*(C'\fR instead.  Similar to <>, also known
as \*(L"readline\*(R" in perlfunc.
.IP "fileno" 8
.IX Item "fileno"
Use method \f(CW\*(C`IO::Handle::fileno()\*(C'\fR instead, or see \*(L"fileno\*(R" in perlfunc.
.IP "floor" 8
.IX Item "floor"
This is identical to the C function \f(CW\*(C`floor()\*(C'\fR, returning the largest
integer value less than or equal to the numerical argument.
.IP "fmod" 8
.IX Item "fmod"
This is identical to the C function \f(CW\*(C`fmod()\*(C'\fR.
.Sp
.Vb 1
\&        $r = fmod($x, $y);
.Ve
.Sp
It returns the remainder \f(CW\*(C`$r = $x \- $n*$y\*(C'\fR, where \f(CW\*(C`$n = trunc($x/$y)\*(C'\fR.
The \f(CW$r\fR has the same sign as \f(CW$x\fR and magnitude (absolute value)
less than the magnitude of \f(CW$y\fR.
.IP "fopen" 8
.IX Item "fopen"
Use method \f(CW\*(C`IO::File::open()\*(C'\fR instead, or see \*(L"open\*(R" in perlfunc.
.IP "fork" 8
.IX Item "fork"
This is identical to Perl's builtin \f(CW\*(C`fork()\*(C'\fR function
for duplicating the current process, see \*(L"fork\*(R" in perlfunc
and perlfork if you are in Windows.
.IP "fpathconf" 8
.IX Item "fpathconf"
Retrieves the value of a configurable limit on a file or directory.  This
uses file descriptors such as those obtained by calling \f(CW\*(C`POSIX::open\*(C'\fR.
.Sp
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds \f(CW\*(C`/var/foo\*(C'\fR.
.Sp
.Vb 2
\&        $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
\&        $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
.Ve
.Sp
Returns \f(CW\*(C`undef\*(C'\fR on failure.
.IP "fprintf" 8
.IX Item "fprintf"
\&\fIfprintf()\fR is C\-specific, see \*(L"printf\*(R" in perlfunc instead.
.IP "fputc" 8
.IX Item "fputc"
\&\fIfputc()\fR is C\-specific, see \*(L"print\*(R" in perlfunc instead.
.IP "fputs" 8
.IX Item "fputs"
\&\fIfputs()\fR is C\-specific, see \*(L"print\*(R" in perlfunc instead.
.IP "fread" 8
.IX Item "fread"
\&\fIfread()\fR is C\-specific, see \*(L"read\*(R" in perlfunc instead.
.IP "free" 8
.IX Item "free"
\&\fIfree()\fR is C\-specific.  Perl does memory management transparently.
.IP "freopen" 8
.IX Item "freopen"
\&\fIfreopen()\fR is C\-specific, see \*(L"open\*(R" in perlfunc instead.
.IP "frexp" 8
.IX Item "frexp"
Return the mantissa and exponent of a floating-point number.
.Sp
.Vb 1
\&        ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
.Ve
.IP "fscanf" 8
.IX Item "fscanf"
\&\fIfscanf()\fR is C\-specific, use <> and regular expressions instead.
.IP "fseek" 8
.IX Item "fseek"
Use method \f(CW\*(C`IO::Seekable::seek()\*(C'\fR instead, or see \*(L"seek\*(R" in perlfunc.
.IP "fsetpos" 8
.IX Item "fsetpos"
Use method \f(CW\*(C`IO::Seekable::setpos()\*(C'\fR instead, or seek \*(L"seek\*(R" in perlfunc.
.IP "fstat" 8
.IX Item "fstat"
Get file status.  This uses file descriptors such as those obtained by
calling \f(CW\*(C`POSIX::open\*(C'\fR.  The data returned is identical to the data from
Perl's builtin \f(CW\*(C`stat\*(C'\fR function.
.Sp
.Vb 2
\&        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
\&        @stats = POSIX::fstat( $fd );
.Ve
.IP "fsync" 8
.IX Item "fsync"
Use method \f(CW\*(C`IO::Handle::sync()\*(C'\fR instead.
.IP "ftell" 8
.IX Item "ftell"
Use method \f(CW\*(C`IO::Seekable::tell()\*(C'\fR instead, or see \*(L"tell\*(R" in perlfunc.
.IP "fwrite" 8
.IX Item "fwrite"
\&\fIfwrite()\fR is C\-specific, see \*(L"print\*(R" in perlfunc instead.
.IP "getc" 8
.IX Item "getc"
This is identical to Perl's builtin \f(CW\*(C`getc()\*(C'\fR function,
see \*(L"getc\*(R" in perlfunc.
.IP "getchar" 8
.IX Item "getchar"
Returns one character from \s-1STDIN\s0.  Identical to Perl's \f(CW\*(C`getc()\*(C'\fR,
see \*(L"getc\*(R" in perlfunc.
.IP "getcwd" 8
.IX Item "getcwd"
Returns the name of the current working directory.
See also Cwd.
.IP "getegid" 8
.IX Item "getegid"
Returns the effective group identifier.  Similar to Perl' s builtin
variable \f(CW$(\fR, see \*(L"$EGID\*(R" in perlvar.
.IP "getenv" 8
.IX Item "getenv"
Returns the value of the specified environment variable.
The same information is available through the \f(CW%ENV\fR array.
.IP "geteuid" 8
.IX Item "geteuid"
Returns the effective user identifier.  Identical to Perl's builtin \f(CW$>\fR
variable, see \*(L"$EUID\*(R" in perlvar.
.IP "getgid" 8
.IX Item "getgid"
Returns the user's real group identifier.  Similar to Perl's builtin
variable \f(CW$)\fR, see \*(L"$GID\*(R" in perlvar.
.IP "getgrgid" 8
.IX Item "getgrgid"
This is identical to Perl's builtin \f(CW\*(C`getgrgid()\*(C'\fR function for
returning group entries by group identifiers, see
\&\*(L"getgrgid\*(R" in perlfunc.
.IP "getgrnam" 8
.IX Item "getgrnam"
This is identical to Perl's builtin \f(CW\*(C`getgrnam()\*(C'\fR function for
returning group entries by group names, see \*(L"getgrnam\*(R" in perlfunc.
.IP "getgroups" 8
.IX Item "getgroups"
Returns the ids of the user's supplementary groups.  Similar to Perl's
builtin variable \f(CW$)\fR, see \*(L"$GID\*(R" in perlvar.
.IP "getlogin" 8
.IX Item "getlogin"
This is identical to Perl's builtin \f(CW\*(C`getlogin()\*(C'\fR function for
returning the user name associated with the current session, see
\&\*(L"getlogin\*(R" in perlfunc.
.IP "getpgrp" 8
.IX Item "getpgrp"
This is identical to Perl's builtin \f(CW\*(C`getpgrp()\*(C'\fR function for
returning the process group identifier of the current process, see
\&\*(L"getpgrp\*(R" in perlfunc.
.IP "getpid" 8
.IX Item "getpid"
Returns the process identifier.  Identical to Perl's builtin
variable \f(CW$$\fR, see \*(L"$PID\*(R" in perlvar.
.IP "getppid" 8
.IX Item "getppid"
This is identical to Perl's builtin \f(CW\*(C`getppid()\*(C'\fR function for
returning the process identifier of the parent process of the current
process , see \*(L"getppid\*(R" in perlfunc.
.IP "getpwnam" 8
.IX Item "getpwnam"
This is identical to Perl's builtin \f(CW\*(C`getpwnam()\*(C'\fR function for
returning user entries by user names, see \*(L"getpwnam\*(R" in perlfunc.
.IP "getpwuid" 8
.IX Item "getpwuid"
This is identical to Perl's builtin \f(CW\*(C`getpwuid()\*(C'\fR function for
returning user entries by user identifiers, see \*(L"getpwuid\*(R" in perlfunc.
.IP "gets" 8
.IX Item "gets"
Returns one line from \f(CW\*(C`STDIN\*(C'\fR, similar to <>, also known
as the \f(CW\*(C`readline()\*(C'\fR function, see \*(L"readline\*(R" in perlfunc.
.Sp
\&\fB\s-1NOTE\s0\fR: if you have C programs that still use \f(CW\*(C`gets()\*(C'\fR, be very
afraid.  The \f(CW\*(C`gets()\*(C'\fR function is a source of endless grief because
it has no buffer overrun checks.  It should \fBnever\fR be used.  The
\&\f(CW\*(C`fgets()\*(C'\fR function should be preferred instead.
.IP "getuid" 8
.IX Item "getuid"
Returns the user's identifier.  Identical to Perl's builtin \f(CW$<\fR variable,
see \*(L"$UID\*(R" in perlvar.
.IP "gmtime" 8
.IX Item "gmtime"
This is identical to Perl's builtin \f(CW\*(C`gmtime()\*(C'\fR function for
converting seconds since the epoch to a date in Greenwich Mean Time,
see \*(L"gmtime\*(R" in perlfunc.
.IP "isalnum" 8
.IX Item "isalnum"
This is identical to the C function, except that it can apply to a
single character or to a whole string.  Note that locale settings may
affect what characters are considered \f(CW\*(C`isalnum\*(C'\fR.  Does not work on
Unicode characters code point 256 or higher.  Consider using regular
expressions and the \f(CW\*(C`/[[:alnum:]]/\*(C'\fR construct instead, or possibly
the \f(CW\*(C`/\ew/\*(C'\fR construct.
.IP "isalpha" 8
.IX Item "isalpha"
This is identical to the C function, except that it can apply to
a single character or to a whole string.  Note that locale settings
may affect what characters are considered \f(CW\*(C`isalpha\*(C'\fR.  Does not work
on Unicode characters code point 256 or higher.  Consider using regular
expressions and the \f(CW\*(C`/[[:alpha:]]/\*(C'\fR construct instead.
.IP "isatty" 8
.IX Item "isatty"
Returns a boolean indicating whether the specified filehandle is connected
to a tty.  Similar to the \f(CW\*(C`\-t\*(C'\fR operator, see \*(L"\-X\*(R" in perlfunc.
.IP "iscntrl" 8
.IX Item "iscntrl"
This is identical to the C function, except that it can apply to
a single character or to a whole string.  Note that locale settings
may affect what characters are considered \f(CW\*(C`iscntrl\*(C'\fR.  Does not work
on Unicode characters code point 256 or higher.  Consider using regular
expressions and the \f(CW\*(C`/[[:cntrl:]]/\*(C'\fR construct instead.
.IP "isdigit" 8
.IX Item "isdigit"
This is identical to the C function, except that it can apply to
a single character or to a whole string.  Note that locale settings
may affect what characters are considered \f(CW\*(C`isdigit\*(C'\fR (unlikely, but
still possible). Does not work on Unicode characters code point 256
or higher.  Consider using regular expressions and the \f(CW\*(C`/[[:digit:]]/\*(C'\fR
construct instead, or the \f(CW\*(C`/\ed/\*(C'\fR construct.
.IP "isgraph" 8
.IX Item "isgraph"
This is identical to the C function, except that it can apply to
a single character or to a whole string.  Note that locale settings