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Comment by polegone | Hacker News Reader

I am a novice, and that is one of the reasons why I started this project (to learn).

    bytes, _ := ioutil.ReadAll(os.Stdin)
    lines := strings.Split(string(bytes), "\n")

Tip: use bufio.Scanner.

    scanner := bufio.NewScanner(reader)
    scanner.Split(bufio.ScanLines)
    for scanner.Scan() {
      // Do stuff
    }

And you can iterate over the lines 'lazily'. If you don't want to consume \r's, make your own ScanLines :).

Tail also doesn't always need to read its entire input. When given a file path, it can read backwards from the end of the file until it has found its n lines. That makes tail fast on huge files (as long as they have normal line lengths), but it also complicates the code.

And you may want to mmap the file, rather than open it. Whether that is a speeds up things depends on OS, OS version, file size, file system, available memory, phase of the moon, etc.

The problem is something like tail should not read the whole file into memory. tail works on a 100 gig file even with 100 megs of ram.

Great going. This will also help other novice Go programmers learning the language, at the same time getting a sense of how to implement their own Unix commands.

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