This is a unix commandline filter handy for summarising quick greps in logs.
For example: grep stuff /path/to/apache/combined/log | count FIELD-NUMBER
such as wondering who is causing all the 404s?
$ grep ' 404 ' /path/to/apache/combined.log | count 0
Summary for field 0
11.80.43.243 4 50.00%
22.85.35.198 1 12.50%
33.6.17.183 1 12.50%
44.246.146.130 1 12.50%
55.249.67.57 1 12.50%
-------------- - -------
8 100.00%
and you can also get a quicker visual histogram:
$ grep ' 404 ' /path/to/apache/combined.log | count --histogram 0
Summary for field 0
11.80.43.243 4 50.00% ##############################
22.85.35.198 1 12.50% #######
33.6.17.183 1 12.50% #######
44.246.146.130 1 12.50% #######
55.249.67.57 1 12.50% #######
-------------- - -------
8 100.00% ############################################################