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Accepted
Sonny
Asked: 2014-08-12 09:29:14 +0800 CST

tail: Reading an entire file, and then following

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I would like a tail -f type of behavior that reads the entire file and then continues to follow it as it's written to.

SOLUTION

Based on the answer I accepted, this works: tail -f -n +1 {filename}

Why it works: The -f option continues to "follow" the file and output new lines as they are written to the file. The -n +1 instructs tail to start reading the file from the first line. Using -n -10 would start with the last ten lines of the file.

tail

2 Answers

  1. Best Answer

    Use

    tail -f -n +1

    Using man tail will give you more details, the relevant excerpt follows.

    <snip>Numbers having a leading plus (`+') sign are relative to the
beginning of the input, for example, ``-n +2'' starts the display at the
second line of the input.</snip>

-f      The -f option causes tail to not stop when end of file is
        reached, but rather to wait for additional data to be appended to
        the input.  The -f option is ignored if the standard input is a
        pipe, but not if it is a FIFO.

-n number
        The location is number lines.
    • 88

  2. Try this:

    watch tail {filename}

    where {filename} is the file that you want to keep an eye on. This will continuously monitor the command for changes and output the changes to stdout. It's pretty handy.

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