perlrun.1

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.

\&    #!/usr/bin/perl \-spi.orig   # same as \-s \-p \-i.orig
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.PP
Switches include:
.IP "\fB\-0\fR[\fIoctal/hexadecimal\fR]" 5
.IX Xref "-0 $"
.IX Item "-0[octal/hexadecimal]"
specifies the input record separator (\f(CW$/\fR) as an octal or
hexadecimal number.  If there are no digits, the null character is the
separator.  Other switches may precede or follow the digits.  For
example, if you have a version of \fBfind\fR which can print filenames
terminated by the null character, you can say this:
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.Vb 1
\&    find . \-name \*(Aq*.orig\*(Aq \-print0 | perl \-n0e unlink
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The special value 00 will cause Perl to slurp files in paragraph mode.
The value 0777 will cause Perl to slurp files whole because there is no
legal byte with that value.
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If you want to specify any Unicode character, use the hexadecimal
format: \f(CW\*(C`\-0xHHH...\*(C'\fR, where the \f(CW\*(C`H\*(C'\fR are valid hexadecimal digits.
(This means that you cannot use the \f(CW\*(C`\-x\*(C'\fR with a directory name that
consists of hexadecimal digits.)
.IP "\fB\-a\fR" 5
.IX Xref "-a autosplit"
.IX Item "-a"
turns on autosplit mode when used with a \fB\-n\fR or \fB\-p\fR.  An implicit
split command to the \f(CW@F\fR array is done as the first thing inside the
implicit while loop produced by the \fB\-n\fR or \fB\-p\fR.
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.Vb 1
\&    perl \-ane \*(Aqprint pop(@F), "\en";\*(Aq
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is equivalent to
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.Vb 4
\&    while (<>) {
\&        @F = split(\*(Aq \*(Aq);
\&        print pop(@F), "\en";
\&    }
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An alternate delimiter may be specified using \fB\-F\fR.
.IP "\fB\-C [\f(BInumber/list\fB]\fR" 5
.IX Xref "-C"
.IX Item "-C [number/list]"
The \f(CW\*(C`\-C\*(C'\fR flag controls some of the Perl Unicode features.
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As of 5.8.1, the \f(CW\*(C`\-C\*(C'\fR can be followed either by a number or a list
of option letters.  The letters, their numeric values, and effects
are as follows; listing the letters is equal to summing the numbers.
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.Vb 10
\&    I     1   STDIN is assumed to be in UTF\-8
\&    O     2   STDOUT will be in UTF\-8
\&    E     4   STDERR will be in UTF\-8
\&    S     7   I + O + E
\&    i     8   UTF\-8 is the default PerlIO layer for input streams
\&    o    16   UTF\-8 is the default PerlIO layer for output streams
\&    D    24   i + o
\&    A    32   the @ARGV elements are expected to be strings encoded
\&              in UTF\-8
\&    L    64   normally the "IOEioA" are unconditional,
\&              the L makes them conditional on the locale environment
\&              variables (the LC_ALL, LC_TYPE, and LANG, in the order
\&              of decreasing precedence) \-\- if the variables indicate
\&              UTF\-8, then the selected "IOEioA" are in effect
\&    a   256   Set ${^UTF8CACHE} to \-1, to run the UTF\-8 caching code in
\&              debugging mode.
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For example, \f(CW\*(C`\-COE\*(C'\fR and \f(CW\*(C`\-C6\*(C'\fR will both turn on UTF\-8\-ness on both
\&\s-1STDOUT\s0 and \s-1STDERR\s0.  Repeating letters is just redundant, not cumulative
nor toggling.
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The \f(CW\*(C`io\*(C'\fR options mean that any subsequent \fIopen()\fR (or similar I/O
operations) will have the \f(CW\*(C`:utf8\*(C'\fR PerlIO layer implicitly applied
to them, in other words, \s-1UTF\-8\s0 is expected from any input stream,
and \s-1UTF\-8\s0 is produced to any output stream.  This is just the default,
with explicit layers in \fIopen()\fR and with \fIbinmode()\fR one can manipulate
streams as usual.
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\&\f(CW\*(C`\-C\*(C'\fR on its own (not followed by any number or option list), or the
empty string \f(CW""\fR for the \f(CW\*(C`PERL_UNICODE\*(C'\fR environment variable, has the
same effect as \f(CW\*(C`\-CSDL\*(C'\fR.  In other words, the standard I/O handles and
the default \f(CW\*(C`open()\*(C'\fR layer are UTF\-8\-fied \fBbut\fR only if the locale
environment variables indicate a \s-1UTF\-8\s0 locale.  This behaviour follows
the \fIimplicit\fR (and problematic) \s-1UTF\-8\s0 behaviour of Perl 5.8.0.
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You can use \f(CW\*(C`\-C0\*(C'\fR (or \f(CW"0"\fR for \f(CW\*(C`PERL_UNICODE\*(C'\fR) to explicitly
disable all the above Unicode features.
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The read-only magic variable \f(CW\*(C`${^UNICODE}\*(C'\fR reflects the numeric value
of this setting.  This is variable is set during Perl startup and is
thereafter read-only.  If you want runtime effects, use the three-arg
\&\fIopen()\fR (see \*(L"open\*(R" in perlfunc), the two-arg \fIbinmode()\fR (see \*(L"binmode\*(R" in perlfunc),
and the \f(CW\*(C`open\*(C'\fR pragma (see open).
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(In Perls earlier than 5.8.1 the \f(CW\*(C`\-C\*(C'\fR switch was a Win32\-only switch
that enabled the use of Unicode-aware \*(L"wide system call\*(R" Win32 APIs.
This feature was practically unused, however, and the command line
switch was therefore \*(L"recycled\*(R".)
.IP "\fB\-c\fR" 5
.IX Xref "-c"
.IX Item "-c"
causes Perl to check the syntax of the program and then exit without
executing it.  Actually, it \fIwill\fR execute \f(CW\*(C`BEGIN\*(C'\fR, \f(CW\*(C`UNITCHECK\*(C'\fR,
\&\f(CW\*(C`CHECK\*(C'\fR, and \f(CW\*(C`use\*(C'\fR blocks, because these are considered as occurring
outside the execution of your program.  \f(CW\*(C`INIT\*(C'\fR and \f(CW\*(C`END\*(C'\fR blocks,
however, will be skipped.
.IP "\fB\-d\fR" 5
.IX Xref "-d -dt"
.IX Item "-d"
.PD 0
.IP "\fB\-dt\fR" 5
.IX Item "-dt"
.PD
runs the program under the Perl debugger.  See perldebug.
If \fBt\fR is specified, it indicates to the debugger that threads
will be used in the code being debugged.
.IP "\fB\-d:\fR\fIfoo[=bar,baz]\fR" 5
.IX Xref "-d -dt"
.IX Item "-d:foo[=bar,baz]"
.PD 0
.IP "\fB\-dt:\fR\fIfoo[=bar,baz]\fR" 5
.IX Item "-dt:foo[=bar,baz]"
.PD
runs the program under the control of a debugging, profiling, or
tracing module installed as Devel::foo. E.g., \fB\-d:DProf\fR executes
the program using the Devel::DProf profiler.  As with the \fB\-M\fR
flag, options may be passed to the Devel::foo package where they
will be received and interpreted by the Devel::foo::import routine.
The comma-separated list of options must follow a \f(CW\*(C`=\*(C'\fR character.
If \fBt\fR is specified, it indicates to the debugger that threads
will be used in the code being debugged.
See perldebug.
.IP "\fB\-D\fR\fIletters\fR" 5
.IX Xref "-D DEBUGGING -DDEBUGGING"
.IX Item "-Dletters"
.PD 0
.IP "\fB\-D\fR\fInumber\fR" 5
.IX Item "-Dnumber"
.PD
sets debugging flags.  To watch how it executes your program, use
\&\fB\-Dtls\fR.  (This works only if debugging is compiled into your
Perl.)  Another nice value is \fB\-Dx\fR, which lists your compiled
syntax tree.  And \fB\-Dr\fR displays compiled regular expressions;
the format of the output is explained in perldebguts.
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As an alternative, specify a number instead of list of letters (e.g.,
\&\fB\-D14\fR is equivalent to \fB\-Dtls\fR):
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.Vb 10
\&        1  p  Tokenizing and parsing (with v, displays parse stack)
\&        2  s  Stack snapshots (with v, displays all stacks)
\&        4  l  Context (loop) stack processing
\&        8  t  Trace execution
\&       16  o  Method and overloading resolution
\&       32  c  String/numeric conversions
\&       64  P  Print profiling info, preprocessor command for \-P, source file input state
\&      128  m  Memory allocation
\&      256  f  Format processing
\&      512  r  Regular expression parsing and execution
\&     1024  x  Syntax tree dump
\&     2048  u  Tainting checks
\&     4096  U  Unofficial, User hacking (reserved for private, unreleased use)
\&     8192  H  Hash dump \-\- usurps values()
\&    16384  X  Scratchpad allocation
\&    32768  D  Cleaning up
\&    65536  S  Thread synchronization
\&   131072  T  Tokenising
\&   262144  R  Include reference counts of dumped variables (eg when using \-Ds)
\&   524288  J  Do not s,t,P\-debug (Jump over) opcodes within package DB
\&  1048576  v  Verbose: use in conjunction with other flags
\&  2097152  C  Copy On Write
\&  4194304  A  Consistency checks on internal structures
\&  8388608  q  quiet \- currently only suppresses the "EXECUTING" message
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All these flags require \fB\-DDEBUGGING\fR when you compile the Perl
executable (but see Devel::Peek, re which may change this).
See the \fI\s-1INSTALL\s0\fR file in the Perl source distribution
for how to do this.  This flag is automatically set if you include \fB\-g\fR
option when \f(CW\*(C`Configure\*(C'\fR asks you about optimizer/debugger flags.
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If you're just trying to get a print out of each line of Perl code
as it executes, the way that \f(CW\*(C`sh \-x\*(C'\fR provides for shell scripts,
you can't use Perl's \fB\-D\fR switch.  Instead do this
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.Vb 2
\&  # If you have "env" utility
\&  env PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl \-dS program
\&
\&  # Bourne shell syntax
\&  $ PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl \-dS program
\&
\&  # csh syntax
\&  % (setenv PERLDB_OPTS "NonStop=1 AutoTrace=1 frame=2"; perl \-dS program)
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See perldebug for details and variations.
.IP "\fB\-e\fR \fIcommandline\fR" 5
.IX Xref "-e"
.IX Item "-e commandline"
may be used to enter one line of program.  If \fB\-e\fR is given, Perl
will not look for a filename in the argument list.  Multiple \fB\-e\fR
commands may be given to build up a multi-line script.  Make sure
to use semicolons where you would in a normal program.
.IP "\fB\-E\fR \fIcommandline\fR" 5
.IX Xref "-E"
.IX Item "-E commandline"
behaves just like \fB\-e\fR, except that it implicitly enables all
optional features (in the main compilation unit). See feature.
.IP "\fB\-f\fR" 5
.IX Xref "-f"
.IX Item "-f"
Disable executing \fI\f(CI$Config\fI{sitelib}/sitecustomize.pl\fR at startup.
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Perl can be built so that it by default will try to execute
\&\fI\f(CI$Config\fI{sitelib}/sitecustomize.pl\fR at startup.  This is a hook that
allows the sysadmin to customize how perl behaves.  It can for
instance be used to add entries to the \f(CW@INC\fR array to make perl find
modules in non-standard locations.
.IP "\fB\-F\fR\fIpattern\fR" 5
.IX Xref "-F"
.IX Item "-Fpattern"
specifies the pattern to split on if \fB\-a\fR is also in effect.  The
pattern may be surrounded by \f(CW\*(C`//\*(C'\fR, \f(CW""\fR, or \f(CW\*(Aq\*(Aq\fR, otherwise it will be
put in single quotes. You can't use literal whitespace in the pattern.
.IP "\fB\-h\fR" 5
.IX Xref "-h"
.IX Item "-h"
prints a summary of the options.
.IP "\fB\-i\fR[\fIextension\fR]" 5
.IX Xref "-i in-place"
.IX Item "-i[extension]"
specifies that files processed by the \f(CW\*(C`<>\*(C'\fR construct are to be
edited in-place.  It does this by renaming the input file, opening the
output file by the original name, and selecting that output file as the
default for \fIprint()\fR statements.  The extension, if supplied, is used to
modify the name of the old file to make a backup copy, following these
rules:
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If no extension is supplied, no backup is made and the current file is
overwritten.
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If the extension doesn't contain a \f(CW\*(C`*\*(C'\fR, then it is appended to the
end of the current filename as a suffix.  If the extension does
contain one or more \f(CW\*(C`*\*(C'\fR characters, then each \f(CW\*(C`*\*(C'\fR is replaced
with the current filename.  In Perl terms, you could think of this
as:
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.Vb 1
\&    ($backup = $extension) =~ s/\e*/$file_name/g;
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This allows you to add a prefix to the backup file, instead of (or in
addition to) a suffix:
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.Vb 1
\&    $ perl \-pi\*(Aqorig_*\*(Aq \-e \*(Aqs/bar/baz/\*(Aq fileA    # backup to \*(Aqorig_fileA\*(Aq
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Or even to place backup copies of the original files into another
directory (provided the directory already exists):
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.Vb 1
\&    $ perl \-pi\*(Aqold/*.orig\*(Aq \-e \*(Aqs/bar/baz/\*(Aq fileA # backup to \*(Aqold/fileA.orig\*(Aq
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These sets of one-liners are equivalent:
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.Vb 2
\&    $ perl \-pi \-e \*(Aqs/bar/baz/\*(Aq fileA            # overwrite current file
\&    $ perl \-pi\*(Aq*\*(Aq \-e \*(Aqs/bar/baz/\*(Aq fileA         # overwrite current file
\&
\&    $ perl \-pi\*(Aq.orig\*(Aq \-e \*(Aqs/bar/baz/\*(Aq fileA     # backup to \*(AqfileA.orig\*(Aq
\&    $ perl \-pi\*(Aq*.orig\*(Aq \-e \*(Aqs/bar/baz/\*(Aq fileA    # backup to \*(AqfileA.orig\*(Aq
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From the shell, saying
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.Vb 1
\&    $ perl \-p \-i.orig \-e "s/foo/bar/; ... "
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is the same as using the program:
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.Vb 2
\&    #!/usr/bin/perl \-pi.orig
\&    s/foo/bar/;
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which is equivalent to
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.Vb 10
\&    #!/usr/bin/perl
\&    $extension = \*(Aq.orig\*(Aq;
\&    LINE: while (<>) {
\&        if ($ARGV ne $oldargv) {
\&            if ($extension !~ /\e*/) {
\&                $backup = $ARGV . $extension;
\&            }
\&            else {
\&                ($backup = $extension) =~ s/\e*/$ARGV/g;
\&            }
\&            rename($ARGV, $backup);
\&            open(ARGVOUT, ">$ARGV");
\&            select(ARGVOUT);
\&            $oldargv = $ARGV;
\&        }
\&        s/foo/bar/;
\&    }
\&    continue {
\&        print;  # this prints to original filename
\&    }
\&    select(STDOUT);
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except that the \fB\-i\fR form doesn't need to compare \f(CW$ARGV\fR to \f(CW$oldargv\fR to
know when the filename has changed.  It does, however, use \s-1ARGVOUT\s0 for
the selected filehandle.  Note that \s-1STDOUT\s0 is restored as the default
output filehandle after the loop.
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As shown above, Perl creates the backup file whether or not any output
is actually changed.  So this is just a fancy way to copy files:
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.Vb 3
\&    $ perl \-p \-i\*(Aq/some/file/path/*\*(Aq \-e 1 file1 file2 file3...
\&or
\&    $ perl \-p \-i\*(Aq.orig\*(Aq \-e 1 file1 file2 file3...
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You can use \f(CW\*(C`eof\*(C'\fR without parentheses to locate the end of each input
file, in case you want to append to each file, or reset line numbering
(see example in \*(L"eof\*(R" in perlfunc).
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If, for a given file, Perl is unable to create the backup file as
specified in the extension then it will skip that file and continue on
with the next one (if it exists).
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For a discussion of issues surrounding file permissions and \fB\-i\fR,
see \*(L"Why does Perl let me delete read-only files?  Why does \-i clobber protected files?  Isn't this a bug in Perl?\*(R" in perlfaq5.
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You cannot use \fB\-i\fR to create directories or to strip extensions from
files.
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Perl does not expand \f(CW\*(C`~\*(C'\fR in filenames, which is good, since some
folks use it for their backup files:
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.Vb 1
\&    $ perl \-pi~ \-e \*(Aqs/foo/bar/\*(Aq file1 file2 file3...
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Note that because \fB\-i\fR renames or deletes the original file before
creating a new file of the same name, UNIX-style soft and hard links will
not be preserved.
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Finally, the \fB\-i\fR switch does not impede execution when no
files are given on the command line.  In this case, no backup is made
(the original file cannot, of course, be determined) and processing
proceeds from \s-1STDIN\s0 to \s-1STDOUT\s0 as might be expected.
.IP "\fB\-I\fR\fIdirectory\fR" 5