系统管理工具包: 测试系统的有效性

使用 Getopt::Long 模块分 析的命令行选项。这使您能够指定校验和文件（存储您计算的校验和与其他信息）、是否比较新信息和旧 信息（通过阅读校验和文件的内容）和指定要搜索的基本目录。如果比较该文件，将会更新数据并仅报告 差异。

loadchksumdata() 函数，该函数以方便比较新信息和旧信息的方法加载和分析现有数据文 件。

gendiff report() 函数，该函数将所存储信息的各个字段与当前信息进行实际比较，告诉您 更改了哪些内容。仅当确定已存在某种差异时，才调用此函数。

清单 8. 最终脚本

#!/usr/local/bin/perl
use Digest::MD5;
use IO::File;
use strict;
use File::Find ();
use Getopt::Long;
my $chksumfile = 'chksums.dat';
my $compare = 0;
my $basedir = '/etc';
use vars qw/*name *dir *prune/;
*name   = *File::Find::name;
*dir    = *File::Find::dir;
*prune  = *File::Find::prune;
GetOptions("chksumfile=s" => $chksumfile,
           "compare" => $compare,
           "basedir=s" => $basedir);
my $chksumdata = {};
if ($compare)
{
    loadchksumdata($chksumfile);
}
my $outfile = '';
if (!$compare)
{
    $outfile = IO::File->new($chksumfile,"w");
}
File::Find::find({wanted => &wanted}, $basedir);
if ($compare)
{
    foreach my $file (keys %{$chksumdata})
    {
        print STDERR "Couldn't find $file, but have the info on recordn";
    }
}
sub loadchksumdata
{
    my ($file) = @_;
    open(DATA,$file) or die "Cannot open check sum file $file: $!n";
    while(<DATA>)
    {
        chomp;
        my ($filename,$rest) = split(/:/,$_,2);
        $chksumdata->{$filename} = $_;
    }
    close(DATA);
}
sub wanted {
    next unless (-f $name);
    my $fileinfo = genchksuminfo($name);
    if ($compare)
    {
        if (exists($chksumdata->{$name}))
        {
            if ($chksumdata->{$name} ne $fileinfo)
            {
                print STDERR "Warning: $name differs from that on recordn";
                gendiffreport($chksumdata->{$name}, $fileinfo);
            }
            delete($chksumdata->{$name});
        }
        else
        {
            print STDERR "Warning: Couldn't find $name in existing recordsn";
        }
    }
    else
    {
        printf $outfile ("%sn",$fileinfo);
    }
}
sub gendiffreport
{
    my ($orig,$curr) = @_;
    my @fields = qw/filename chksum device inode mode nlink uid gid size mtime
                 ctime/;
    my @origfields = split(/:/,$orig);
    my @currfields = split(/:/,$curr);
    for(my $i=0;$i<scalar @origfields;$i++)
    {
        if ($origfields[$i] ne $currfields[$i])
        {
            print STDERR "t$fields[$i] differ; was $origfields[$i],
			     now $currfields[$i]n";
        }
    }
}
sub genchksuminfo
{
    my ($file) = @_;
    my $chk = Digest::MD5->new();
    my (@statinfo) = stat($file);
    $chk->add(@statinfo[0,1,2,3,4,5,7,9,10]);
    $chk->addfile(IO::File->new($file));
    return sprintf("%s:%s:%s",
                   $file,$chk->hexdigest,
                   join(':',@statinfo[0,1,2,3,4,5,9,10]));
}

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