定制实施＆QUOT;尾-f＆QUOT;在C功能的 [英] Custom implementation of "tail -f" functionality in C

问题描述

编辑：我用，最后，inotify的。作为stefanB说inotify的是使用的东西。我发现，使用的inotify实现-f模式尾克隆， inotail 。

I used, finally, inotify. As stefanB says, inotify is the thing to use. I found a tail clone that uses inotify to implement the -f mode, inotail.

原来的问题文本：

我想实现一个C项目的尾-f的逻辑，对样机的目的我开发它在python如下：

I'm trying to implement the "tail -f" logic in a C project, for prototyping purposes I developed it in python as follow:

    # A forever loop, each 5 seconds writes a line into file.txt
    from time import *

    while 1:
        sleep(5)
        file = open("file.txt", "a")
        file.write("This is a test\n")
        file.close()

接下来的code如下file.txt的的EOF（由上面的code更新）

The next code follows the eof of file.txt (updated by the code above)

    # tail -f 
    from time import *

    file = open("file.txt", "r")
    file.seek(0, 2)

    while 1:
      line = file.readline()
      if not line:
          sleep(1)
      else:
          print line

    file.close()

所有工作正常，但C实现不工作（有没有检查错误code）。省略stdio.h中，文件string.h和unistd.h中的夹杂物（上色隐藏标题包含code）。

All works fine but the C implementation is not working (there are no check-error code). The inclusion of stdio.h, string.h and unistd.h is omitted (the colorization hides the header inclusion code).

    #define LINE_LEN 256

    int main(int argc, char **argv)
    {
        FILE *f;
        char line[LINE_LEN];

        f = fopen("file.txt", "r");

        fseek(f, 0, SEEK_END);

        while (1)
        {
            fgets(line, LINE_LEN, f);

            if (strlen(line) == 0)
            {
                sleep(1);
            }
            else
            {
                printf("Readed: %s", line);
            } 
        }

        fclose(f);

        return 0;
    }

一些想法？

时的一个民意调查是个好主意实现它（）代替presented解决方案？

Is a good idea implement it with a poll() instead the presented solution?.

先谢谢了。

推荐答案

修改：
好像 inotify的是用的东西。自2.6.13应该包含在Linux内核。 从IBM developerWorks上有关inotify的<一篇文章/ A>

EDIT: Seems like inotify is the thing to use. It should be included in linux kernel since 2.6.13 . An article from IBM developerworks about inotify.

previous答案：

Previous answer:

看一看Linux的文件变更监视器（在Linux内核2.4。 X>）。这是一个框架，它可以让你订阅文件更改，你从内核得到回调时发生变更。这应该是比轮询更好。

Have a look at Linux File Alteration Monitor (in linux kernels 2.4.x >). It's a framework that let's you subscribe for file changes and you get callback from kernel when change happens. This should be better than polling.

<一个href=\"http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0650&db=bks&fname=/SGI%5FDeveloper/books/IIDsktp%5FIG/sgi%5Fhtml/ch08.html\"相对=nofollow>范例如何轮询文件更改，检查出部分的等待文件的修改和轮询文件更改

Examples how to poll for file changes, check out sections Waiting for file changes and Polling for file changes.

我还没有尝试过呢。

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