This will give you a binary of the fuzzer, called ``pcre_fuzzer``.
Now, create a directory that will hold the test corpus::
mkdir -p CORPUS
For simple input languages like regular expressions this is all you need.
For more complicated inputs populate the directory with some input samples.
Now run the fuzzer with the corpus dir as the only parameter::
./pcre_fuzzer ./CORPUS
You will see output like this::
Seed: 1876794929
#0 READ cov 0 bits 0 units 1 exec/s 0
#1 pulse cov 3 bits 0 units 1 exec/s 0
#1 INITED cov 3 bits 0 units 1 exec/s 0
#2 pulse cov 208 bits 0 units 1 exec/s 0
#2 NEW cov 208 bits 0 units 2 exec/s 0 L: 64
#3 NEW cov 217 bits 0 units 3 exec/s 0 L: 63
#4 pulse cov 217 bits 0 units 3 exec/s 0
* The ``Seed:`` line shows you the current random seed (you can change it with ``-seed=N`` flag).
* The ``READ`` line shows you how many input files were read (since you passed an empty dir there were inputs, but one dummy input was synthesised).
* The ``INITED`` line shows you that how many inputs will be fuzzed.
* The ``NEW`` lines appear with the fuzzer finds a new interesting input, which is saved to the CORPUS dir. If multiple corpus dirs are given, the first one is used.
* The ``pulse`` lines appear periodically to show the current status.
Now, interrupt the fuzzer and run it again the same way. You will see::
Seed: 1879995378
#0 READ cov 0 bits 0 units 564 exec/s 0
#1 pulse cov 502 bits 0 units 564 exec/s 0
...
#512 pulse cov 2933 bits 0 units 564 exec/s 512
#564 INITED cov 2991 bits 0 units 344 exec/s 564
#1024 pulse cov 2991 bits 0 units 344 exec/s 1024
#1455 NEW cov 2995 bits 0 units 345 exec/s 1455 L: 49
This time you were running the fuzzer with a non-empty input corpus (564 items).
As the first step, the fuzzer minimized the set to produce 344 interesting items (the ``INITED`` line)
You may run ``N`` independent fuzzer jobs in parallel on ``M`` CPUs::
