perl CPAN中有一个Tie-File 模块极大方便了对大文件的操作。
该模块用perl的数组代表一个文件，文件的每一行对应数组的一个元素，第一行为元素0，第二回为1，...
文件本身实际并不加载到内存，对数组元素的操作立刻作用到文件里。最大的方便是可以任意指定处理开头结尾的某几行。
基本用法：
use Tie::File;
tie @array, 'Tie::File', filename or die ...;
$array[13] = 'blah'; # line 13 of the file is now 'blah'
print $array[42]; # display line 42 of the file
$n_recs = @array; # how many records are in the file?
$#array -= 2; # chop two records off the end
for (@array) {
s/PERL/Perl/g; # Replace PERL with Perl everywhere in the file
}
# These are just like regular push, pop, unshift, shift, and splice
# Except that they modify the file in the way you would expect
push @array, new recs...;
my $r1 = pop @array;
unshift @array, new recs...;
my $r2 = shift @array;
@old_recs = splice @array, 3, 7, new recs...;
untie @array; # all finished
更多功能请大家参考cpan上的文档。