Command line manipulation of BibTeX files:

* Pretty-printing data bases
* Syntactic checks with error recovery
* Semantic checks
* Sorting and merging of data bases
* Generation of uniform reference keys according to predefined rules or
  according to user specification
* Selecting references used in one publication which are found by
  analyzing an aux file
* Controlled rewriting of fields utilising regular expressions to specify
  the rewriting rules
* Macro (String) expansion to eliminate the need of extra string
  definitions
* Collecting statistics about one or more data bases

WWW: http://www.ctan.org/tex-archive/biblio/bibtex/utils/bibtool/