如何在Perl中锁定文件？

#!/usr/bin/perl

use strict;
use warnings;

open(my $fh, '+<', 'file.txt') or die "Cannot open file: $!";

# 尝试获取文件锁
if (flock($fh, 2)) {
    # 读取文件内容
    my $content = do { local $/; <$fh> };
    print "File content: $content\n";

    # 修改文件内容
    $content =~ s/Perl/Perl is awesome/g;

    # 将修改后的内容写回文件
    seek($fh, 0, 0);
    print $fh $content;
    truncate($fh, tell($fh));

    # 释放文件锁
    flock($fh, 8);
} else {
    print "Cannot lock file\n";
}

close($fh);