Each application has its help:
Usage: blockMesh [OPTIONS]
options:
-blockTopology write block edges and centres as .obj files
-case <dir> specify alternate case directory, default is the cwd
-dict <file> specify alternative dictionary for the blockMesh description
-noFunctionObjects
do not execute functionObjects
-region <name> specify alternative mesh region
-srcDoc display source code in browser
-doc display application documentation in browser
-help print the usage
Using: OpenFOAM-2.2.1 (see www.OpenFOAM.org)
Build: 2.2.1-57f3c3617a2d