Perl-18---目录操作函数

发布时间：2020-12-16 00:43:39 所属栏目：大数据来源：网络整理

导读：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 functi

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 <KWILLIAMS@cpan.org>

??? 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.