Checkmol is a command-line utility program which reads molecular
structure files in different formats and analyzes the input
molecule for the presence of various functional groups and structural
elements. At present, approx. 200 different functional groups are
recognized. This output can be easily placed into a database table,
permitting the creation of chemical databases with a functional group
search option. Checkmol also outputs a set of statistical values derived
from a given molecule, which can also be used for quick retrieval from a
database. These values include: the number of atoms, bonds, and rings,
the number of differently hybridized carbon, oxgen, and nitrogen atoms,
the number of C=O double bonds, the number of rings of different sizes,
the number of rings containing nitrogen, oxygen, sulfur, the number of
aromatic rings, the number of heterocyclic rings, etc. The combination
of all of these values for a given molecule represents some kind of
"fingerprint" which is useful for rapid pre-selection in a database
structure/substructure search prior to a full atom-by-atom match.

Matchmol complements the capabilities of checkmol. It compares two (or
more) molecular structures and determines whether one of them is a
substructure of the other one. This is done by a full atom-by-atom
comparison of the input structures. Thus, matchmol can be used as a
back-end program for structure/substructure search operations in
chemical databases.

The port installs both checkmol and matchmol.

WWW: http://merian.pch.univie.ac.at/~nhaider/cheminf/cmmm.html