linux - Perl inotify2 每次文件修改触发两次

Question

我正在编写一个 Perl 脚本来监视文件的更改。

#!/usr/bin/perl
use strict;
use Linux::Inotify2;

my $inotify = new Linux::Inotify2 or die $!;
my $filename = "/tmp/foo";
my $counter = 0;

$inotify->watch (
    $filename,
    IN_MODIFY,
    sub {
        ++$counter;
        print "changed: $counter\n";
    }
) or die $!;

1 while $inotify->poll;

如果我这样测试它，每次/tmp/foo 更改时都会调用此处理程序两次(两次递增 $counter):

echo abc > /tmp/foo

为什么？

Answer 1

按照@Lajos Veres 的建议使用>>，或者观察CLOSE_WRITE 事件(对于Linux::Inotify2 是IN_CLOSE_WRITE模块)，

echo > /tmp/foo

---

inotifywait -m /tmp/foo
Setting up watches.
Watches established.
/tmp/foo MODIFY
/tmp/foo OPEN
/tmp/foo MODIFY
/tmp/foo CLOSE_WRITE,CLOSE