file::path.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.

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.\" ========================================================================
.\"
.IX Title "File::Path 3"
.TH File::Path 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.
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.nh
.SH "NAME"
File::Path \- Create or remove directory trees
.SH "VERSION"
.IX Header "VERSION"
This document describes version 2.04 of File::Path, released
2007\-11\-13.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use File::Path;
\&
\&    # modern
\&    mkpath( \*(Aqfoo/bar/baz\*(Aq, \*(Aq/zug/zwang\*(Aq, {verbose => 1} );
\&
\&    rmtree(
\&        \*(Aqfoo/bar/baz\*(Aq, \*(Aq/zug/zwang\*(Aq,
\&        { verbose => 1, error  => \emy $err_list }
\&    );
\&
\&    # traditional
\&    mkpath([\*(Aq/foo/bar/baz\*(Aq, \*(Aqblurfl/quux\*(Aq], 1, 0711);
\&    rmtree([\*(Aqfoo/bar/baz\*(Aq, \*(Aqblurfl/quux\*(Aq], 1, 1);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \f(CW\*(C`mkpath\*(C'\fR function provides a convenient way to create directories
of arbitrary depth. Similarly, the \f(CW\*(C`rmtree\*(C'\fR function provides a
convenient way to delete an entire directory subtree from the
filesystem, much like the Unix command \f(CW\*(C`rm \-r\*(C'\fR.
.PP
Both functions may be called in one of two ways, the traditional,
compatible with code written since the dawn of time, and modern,
that offers a more flexible and readable idiom. New code should use
the modern interface.
.Sh "\s-1FUNCTIONS\s0"
.IX Subsection "FUNCTIONS"
The modern way of calling \f(CW\*(C`mkpath\*(C'\fR and \f(CW\*(C`rmtree\*(C'\fR is with a list
of directories to create, or remove, respectively, followed by an
optional hash reference containing keys to control the
function's behaviour.
.PP
\fI\f(CI\*(C`mkpath\*(C'\fI\fR
.IX Subsection "mkpath"
.PP
The following keys are recognised as parameters to \f(CW\*(C`mkpath\*(C'\fR.
The function returns the list of files actually created during the
call.
.PP
.Vb 5
\&  my @created = mkpath(
\&    qw(/tmp /flub /home/nobody),
\&    {verbose => 1, mode => 0750},
\&  );
\&  print "created $_\en" for @created;
.Ve
.IP "mode" 4
.IX Item "mode"
The numeric permissions mode to apply to each created directory
(defaults to 0777), to be modified by the current \f(CW\*(C`umask\*(C'\fR. If the
directory already exists (and thus does not need to be created),
the permissions will not be modified.
.Sp
\&\f(CW\*(C`mask\*(C'\fR is recognised as an alias for this parameter.
.IP "verbose" 4
.IX Item "verbose"
If present, will cause \f(CW\*(C`mkpath\*(C'\fR to print the name of each directory
as it is created. By default nothing is printed.
.IP "error" 4
.IX Item "error"
If present, will be interpreted as a reference to a list, and will
be used to store any errors that are encountered.  See the \s-1ERROR\s0
\&\s-1HANDLING\s0 section for more information.
.Sp
If this parameter is not used, certain error conditions may raise
a fatal error that will cause the program will halt, unless trapped
in an \f(CW\*(C`eval\*(C'\fR block.
.PP
\fI\f(CI\*(C`rmtree\*(C'\fI\fR
.IX Subsection "rmtree"
.IP "verbose" 4
.IX Item "verbose"
If present, will cause \f(CW\*(C`rmtree\*(C'\fR to print the name of each file as
it is unlinked. By default nothing is printed.
.IP "safe" 4
.IX Item "safe"
When set to a true value, will cause \f(CW\*(C`rmtree\*(C'\fR to skip the files
for which the process lacks the required privileges needed to delete
files, such as delete privileges on \s-1VMS\s0. In other words, the code
will make no attempt to alter file permissions. Thus, if the process
is interrupted, no filesystem object will be left in a more
permissive mode.
.IP "keep_root" 4
.IX Item "keep_root"
When set to a true value, will cause all files and subdirectories
to be removed, except the initially specified directories. This comes
in handy when cleaning out an application's scratch directory.
.Sp
.Vb 1
\&  rmtree( \*(Aq/tmp\*(Aq, {keep_root => 1} );
.Ve
.IP "result" 4
.IX Item "result"
If present, will be interpreted as a reference to a list, and will
be used to store the list of all files and directories unlinked
during the call. If nothing is unlinked, a reference to an empty
list is returned (rather than \f(CW\*(C`undef\*(C'\fR).
.Sp
.Vb 2
\&  rmtree( \*(Aq/tmp\*(Aq, {result => \emy $list} );
\&  print "unlinked $_\en" for @$list;
.Ve
.Sp
This is a useful alternative to the \f(CW\*(C`verbose\*(C'\fR key.
.IP "error" 4
.IX Item "error"
If present, will be interpreted as a reference to a list,
and will be used to store any errors that are encountered.
See the \s-1ERROR\s0 \s-1HANDLING\s0 section for more information.
.Sp
Removing things is a much more dangerous proposition than
creating things. As such, there are certain conditions that
\&\f(CW\*(C`rmtree\*(C'\fR may encounter that are so dangerous that the only
sane action left is to kill the program.
.Sp
Use \f(CW\*(C`error\*(C'\fR to trap all that is reasonable (problems with
permissions and the like), and let it die if things get out
of hand. This is the safest course of action.
.Sh "\s-1TRADITIONAL\s0 \s-1INTERFACE\s0"
.IX Subsection "TRADITIONAL INTERFACE"
The old interfaces of \f(CW\*(C`mkpath\*(C'\fR and \f(CW\*(C`rmtree\*(C'\fR take a reference to
a list of directories (to create or remove), followed by a series
of positional, numeric, modal parameters that control their behaviour.
.PP
This design made it difficult to add additional functionality, as
well as posed the problem of what to do when the calling code only
needs to set the last parameter. Even though the code doesn't care
how the initial positional parameters are set, the programmer is
forced to learn what the defaults are, and specify them.
.PP
Worse, if it turns out in the future that it would make more sense
to change the default behaviour of the first parameter (for example,
to avoid a security vulnerability), all existing code will remain
hard-wired to the wrong defaults.
.PP
Finally, a series of numeric parameters are much less self-documenting
in terms of communicating to the reader what the code is doing. Named
parameters do not have this problem.
.PP
In the traditional \s-1API\s0, \f(CW\*(C`mkpath\*(C'\fR takes three arguments:
.IP "\(bu" 4
The name of the path to create, or a reference to a list of paths
to create,
.IP "\(bu" 4
a boolean value, which if \s-1TRUE\s0 will cause \f(CW\*(C`mkpath\*(C'\fR to print the
name of each directory as it is created (defaults to \s-1FALSE\s0), and
.IP "\(bu" 4
the numeric mode to use when creating the directories (defaults to
0777), to be modified by the current umask.
.PP
It returns a list of all directories (including intermediates, determined
using the Unix '/' separator) created.  In scalar context it returns
the number of directories created.
.PP