遍历文件夹方法主要有三种
1. 使用File::Find;
2. 递归遍历。(遍历函数为lsr)
3.
使用队列或栈遍历。(遍历函数为lsr_s)1.use File::Find
#!/usr/bin/perl -W
#
#
File: find.pl
# Author: 路小佳
# License: GPL-2use strict;
use
warnings;
use File::Find;my ($size, $dircnt, $filecnt) = (0, 0,
0);sub process {
my $file = $File::Find::name;
#print $file,
"\n";
if (-d $file) {
$dircnt++;
}
else {
$filecnt++;
$size +=
-s $file;
}
}find(\&process, '.');
print "$filecnt files,
$dircnt directory. $size bytes.\n";2. lsr递归遍历
#!/usr/bin/perl
-W
#
# File: lsr.pl
# Author: 路小佳
# License: GPL-2use
strict;
use warnings;sub lsr($) {
sub lsr;
my $cwd =
shift;local *DH;
if (!opendir(DH, $cwd)) {
warn "Cannot opendir
$cwd: $! $^E";
return undef;
}
foreach (readdir(DH)) {
if ($_ eq '.'
|| $_ eq '..') {
next;
}
my $file = $cwd.'/'.$_;
if (!-l $file
&& -d _) {
$file .= '/';
lsr($file);
}
process($file,
$cwd);
}
closedir(DH);
}my ($size, $dircnt, $filecnt) = (0, 0,
0);sub process($$) {
my $file = shift;
#print $file, "\n";
if
(substr($file, length($file)-1, 1) eq '/') {
$dircnt++;
}
else
{
$filecnt++;
$size += -s $file;
}
}lsr('.');
print
"$filecnt files, $dircnt directory. $size bytes.\n";3.
lsr_s栈遍历
#!/usr/bin/perl -W
#
# File: lsr_s.pl
# Author: 路小佳
#
License: GPL-2use strict;
use warnings;sub lsr_s($) {
my
$cwd = shift;
my @dirs = ($cwd.'/');my ($dir, $file);
while ($dir
= pop(@dirs)) {
local *DH;
if (!opendir(DH, $dir)) {
warn "Cannot
opendir $dir: $! $^E";
next;
}
foreach (readdir(DH)) {
if ($_ eq '.'
|| $_ eq '..') {
next;
}
$file = $dir.$_;
if (!-l $file &&
-d _) {
$file .= '/';
push(@dirs, $file);
}
process($file,
$dir);
}
closedir(DH);
}
}my ($size, $dircnt, $filecnt) =
(0, 0, 0);sub process($$) {
my $file = shift;
print $file,
"\n";
if (substr($file, length($file)-1, 1) eq '/')
{
$dircnt++;
}
else {
$filecnt++;
$size += -s
$file;
}
}lsr_s('.');
print "$filecnt files, $dircnt directory.
$size bytes.\n";对我的硬盘/dev/hda6的测试结果。
1: File::Find
26881 files,
1603 directory. 9052479946 bytes.real 0m9.140s
user 0m3.124s
sys
0m5.811s2: lsr
26881 files, 1603 directory. 9052479946
bytes.real 0m8.266s
user 0m2.686s
sys 0m5.405s3:
lsr_s
26881 files, 1603 directory. 9052479946 bytes.real
0m6.532s
user 0m2.124s
sys 0m3.952s测试时考虑到cache所以要多测几次取平均,
也不要同时打印文件名， 因为控制台是慢设备， 会形成瓶颈。
lsr_s之所以用栈而不是队列来遍历，是因为Perl的push shift
pop操作是基于数组的， push pop这样成对操作可能有优化。内存和cpu占用大小顺序也是1>2>3.
CPU load
memory
use File::Find 97% 4540K
lsr 95% 3760K
lsr_s 95%
3590K结论:
强烈推荐使用lsr_s来遍历文件夹。=============再罗嗦几句======================
从执行效率上来看，find.pl比lsr.pl的差距主要在user上，
原因是File::Find模块选项较多，条件判断费时较多，而 lsr_s.pl比lsr.pl在作系统调用用时较少，
是因为递归时程序还在保存原有的文件句柄和函数恢复现场的信息，所以sys费时较多。 所以
lsr_s在sys与user上同时胜出是不无道理的。#!/usr/bin/perl
-w
#读取目录下的目录，并且去除..和.目录以及隐藏的目录
opendir (DIR,"/root") or die "could not
open /root";
@dots=grep {/^[^\.]/ && -d "/root/$_" }
readdir(DIR);
foreach (@dots) {
print "$_\n";
}
closedir
DIR;#!/usr/bin/perl# A small program to read the contents
#
of a directory and print them to
screen@dir_contents;
$dir_to_open="/home/sant/dcs/Teaching/Internet_Systems/Lectures";#
open file with handle DIRopendir(DIR,$dir_to_open) || die("Cannot open
directory !\n");# Get contents of directory@dir_contents=
readdir(DIR);# Close the directoryclosedir(DIR);# Now
loop through array and print file namesforeach $file
(@dir_contents)
{
if(!(($file eq ".") || ($file eq "..")))
{
print
"$file \n";
}
}