To install flawfinder:

If you use an RPM-based system (e.g., Red Hat) or deb-based system
(e.g., Debian), use their respective RPM or debian installation program
and just install it; then ignore the rest of these instructions.
For a ports-based system where you have a current port, just use that.

Otherwise, you'll need to install from the tarball.
So, here's how to do that.

* Install the "tarball" and uncompress it.
  GNU-based systems can run "tar xvzf flawfinder*.tar.gz" to do so,
  then "cd" into the directory created.  If that doesn't work
  (e.g., you have an old tar program), use:
    gunzip flawfinder*.tar.gz
    tar xvf flawfinder*.tar
    cd flawfinder-*

* Decide where you want to put it.  Flawfinder normally installs
  in /usr/local, with the program in /usr/local/bin and the manual in
  /usr/local/man, per GNU conventions.  You can override this
  using the normal GNU conventions when installing (with "make install")
  by setting INSTALL_DIR (defaults to /usr/local),
  INSTALL_DIR_BIN for the program location (defaults to INSTALL_DIR/bin), and
  INSTALL_DIR_MAN for the manual location (defaults to INSTALL_DIR/man).

* If you're using Cygwin on Windows, you can install it using "make install"
  but you need to tell the makefile to use the .py extension
  whenever you use make.  This will be another make install override.
  If you'll just install it, do this:

  make PYTHONEXT=.py install

  If you don't want to pass the "PYTHONEXT" extension each time,
  you can change the file "makefile" to remember this. Just change
  the line beginning with "PYTHONEXT=" so that it reads as follows:
  PYTHONEXT=.py

* Now install it, giving whatever overrides you need.
  In most cases, you'll need to be root, so run this first:
  su

  Then give the "make install" command appropriate for your system.
  For an all-default installation, which is what you need for most cases:
  make install

  (you need to be root; "make uninstall" reverses it).

  To install in /usr (the program in /usr/bin, the manual in /usr/man):
  make INSTALL_DIR=/usr install

  To put the binaries in /usr/bin, and the manuals in /usr/share/man
  (common for Red Hat Linux), do:
  make INSTALL_DIR=/usr INSTALL_DIR_MAN=/usr/share/man install


* Windows systems should be able to run this on the command line (cmd.exe)
  directly, but I haven't tried that.

* You can also simply run the program in the directory you've unpacked it
  into.   It's a simple Python program, just type into a command line:

  ./flawfinder files_or_directory