Perl-18---目录 *** 作函数_语言综合

概述一、读取当前目录： NAME Cwd - get pathname of current working directory SYNOPSIS use Cwd; my $dir = getcwd; use Cwd 'abs_path'; my $abs_path = abs_path($file); DESCRIPTION

一、读取当前目录：

name
Cwd - get pathname of current working directory

SYnopSIS
use Cwd;
my $dir = getcwd;

use Cwd 'abs_path';
my $abs_path = abs_path($file);

DESCRIPTION
    This module provIDes functions for determining the pathname of the
    current working directory. It is recommended that getcwd (or another
    *cwd() function) be used in *all* code to ensure portability.

By default,it exports the functions cwd(),getcwd(),fastcwd(),and
fastgetcwd() (and,on Win32,getdcwd()) into the caller's namespace.

getcwd and frIEnds
Each of these functions are called without arguments and return the
absolute path of the current working directory.

getcwd
my $cwd = getcwd();

Returns the current working directory.

Exposes the POSIX function getcwd(3) or re-implements it if it's not
available.

cwd
my $cwd = cwd();

        The cwd() is the most natural form for the current architecture. For
        most systems it is IDentical to `pwd` (but without the trailing line
        terminator).

fastcwd
my $cwd = fastcwd();

A more dangerous version of getcwd(),but potentially faster.

        It might conceivably chdir() you out of a directory that it can't
        chdir() you back into. If fastcwd encounters a problem it will
        return undef but will probably leave you in a different directory.
        For a measure of extra security,if everything appears to have
        worked,the fastcwd() function will check that it leaves you in the
        same directory that it started in. If it has changed it will "dIE"
        with the message "Unstable directory path,current directory changed
        unexpectedly". That should never happen.

fastgetcwd
my $cwd = fastgetcwd();

The fastgetcwd() function is provIDed as a synonym for cwd().

    getdcwd
            my $cwd = getdcwd();
            my $cwd = getdcwd('C:');

        The getdcwd() function is also provIDed on Win32 to get the current
        working directory on the specifIEd drive,since windows maintains a
        separate current working directory for each drive. If no drive is
        specifIEd then the current drive is assumed.

This function simply calls the Microsoft C library _getdcwd()
function.

abs_path and frIEnds
    These functions are exported only on request. They each take a single
    argument and return the absolute pathname for it. If no argument is
    given they'll use the current working directory.

abs_path
my $abs_path = abs_path($file);

        Uses the same algorithm as getcwd(). Symbolic links and
        relative-path components ("." and "..") are resolved to return the
        canonical pathname,just like realpath(3).

realpath
my $abs_path = realpath($file);

A synonym for abs_path().

fast_abs_path
my $abs_path = fast_abs_path($file);

A more dangerous,but potentially faster version of abs_path.

$ENV{PWD}
If you ask to overrIDe your chdir() built-in function,

use Cwd qw(chdir);

    then your PWD environment variable will be kept up to date. Note that it
    will only be kept up to date if all packages which use chdir import it
    from Cwd.

NOTES
    *   Since the path seperators are different on some operating systems
        ('/' on Unix,':' on MacPerl,etc...) we recommend you use the
        file::Spec modules wherever portability is a concern.

    *   Actually,on Mac OS,the "getcwd()","fastgetcwd()" and "fastcwd()"
        functions are all aliases for the "cwd()" function,which,on Mac
        OS,calls `pwd`. likewise,the "abs_path()" function is an alias for
        "fast_abs_path()".

AUTHOR
Originally by the perl5-porters.

Maintained by Ken Williams <[email protected]>

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

    Portions of the C code in this library are copyright (c) 1994 by the
    Regents of the University of California. All rights reserved. The
    license on this code is compatible with the licensing of the rest of the
    distribution - please see the source code in Cwd.xs for the details.

Perl-18---目录 *** 作函数

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