When typing OpenFOAM commands, the bash completion system will
complete option names, e.g. -help, -parallel, etc. After typing an
option that includes an argument, e.g. -case <dir>, completion will
adjust to the type of argument, e.g. present directories if the
argument is a directory. Similarly, for applications with mandarory
file arguments, file (and directory) names will appear on the
completion list.
