Command Line – Utility to Visualize How Fast a File is Growing

mplayer comes with an midentify utility that does mostly what you want.

The output looks like variable assignments, so it is pretty easy to use in scripts/simple to parse.

If midentify isn't installed with your mplayer package, you might have an midentify.sh script in /usr/share/mplayer or something like that. If not, midenfify just runs mplayer with a specific set of arguments:

#!/bin/sh
#
# This is a wrapper around the -identify functionality.
# It is supposed to escape the output properly, so it can be easily
# used in shellscripts by 'eval'ing the output of this script.
#
# Written by Tobias Diedrich <ranma+mplayer@tdiedrich.de>
# Licensed under GNU GPL.

if [ -z "$1" ]; then
        echo "Usage: midentify.sh <file> [<file> ...]"
        exit 1
fi

mplayer -vo null -ao null -frames 0 -identify "$@" 2>/dev/null |
    sed -ne '/^ID_/ {
                      s/[]()|&;<>`'"'"'\\!$" []/\\&/g;p
                    }'

The -ao, -vo and -frames parameters prevent mplayer from actually playing the clip. The rest is just formatting.

Example:

$ midentify some_random.avi 
ID_VIDEO_ID=0
ID_AUDIO_ID=0
...
ID_VIDEO_BITRATE=258488
ID_VIDEO_WIDTH=320
ID_VIDEO_HEIGHT=240
ID_VIDEO_FPS=29.917
...
ID_LENGTH=4216.76
...
ID_AUDIO_BITRATE=64000
ID_AUDIO_RATE=22050
...

Typically this information is not kept -- and if it is, it's going to depend very much on what system you're using.

We can infer from your desired output that you're using a Unix-like system. Unix keeps three timestamps for each file: mtime, ctime, and atime, which are the time of last modification, the time the inode was most recently modified, and the last access time. No deeper history is kept for any of these.

The program you're using to modify the file might keep such information, but that depends on what you're using.

If you want to keep track of such things, you probably want to use a source control system. A number of them are available: RCS, CVS, Subversion (SVN), Git, Mercurial (Hg), and many others. You'll have to explicitly check in your file(s) after modifying them in order for modifications to be tracked. Such a system will also let you retrieve and compare older versions.