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Jason
Asked: 2011-02-04 20:48:25 +0800 CST

Watch syntax help

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In my Systems Programming class, there are weekly programming experiments, and I'm having trouble with the current one.

The objective is to write a C program that slowly writes a string of text to a file, metered by usleep() in a 100 count for loop.

The goal of the experiment is to observe the file size buffer in action via the watch command. However, I can't get it to work using watch -d ./output

What syntax do I need for the watch command to see the changes made to the file size?

command-line

1 Answers

  1. Best Answer

    You can use du to check a file's size (strictly speaking, its disk usage):

    watch -n 1 du output_file

    If you want shorter than one second intervals, you can also execute du in an endless loop, sleeping afterwards for, say, 0.1 seconds:

    while true; do du output_file; sleep 0.1; done

    Or remove the sleep entirely.

    Have a look at man du for more options.

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