Bibtool User Manual:
Bibtool takes multiple command line arguments to create an index of multiple bibliography (.bib) files, and search for key names within the .bib files. The first argument or arguments passed are the bibliography files that need to be indexed. The file names entered must be case sensitive and include the .bib extension. The .bib extension must be either lower case or upper case and must coincide with the actual file. A bibliography file with an extension such as .BiB will not be indexed. Following the bibliography files a index file name may optionally be specified. If this file name is entered the index will be written using the specified file name with a .ndx extension. The bibs file (containing an index of .bib file names) will be written with a .bfs extension. If a index file name is not specified the last .bib file name will be used, the .bib will be purged, and a .ndx and .bfs extension will be added. The user may also specify a file containing key names, authors, or titles to search for in the bibliography files. This should be done by adding a -s followed by the file name containing the key names to search for. If an author is being searched for a single word from the authors name should be preceded by an “a=” and a “t=” if it is a title. If the -s [searchfile] is specified a searchfile.out will be written to disk containing information about where the key name was found. The program is ran with only bibliography filenames as arguments it will only create the .ndx and .bfs index files of all entries in the .bib files.
bibtool datafile1 datafile2 ... datafilen [index_filename] [-s searchList_filename]
bibtool first.bib second.bib bibIndex -s searchNames
Additional features include bibtool's ability to ignore filenames that do not have a .bib extension and to accept .bib filenames that do not exist followed by an error message to the user that bibtool was not able to open the file. If one or more .bib files fails to open it will continue to create the index files using the bibliography file/files that are open-able. It reports all instances of duplicate key names that it finds in any of the .bib files. It is also able to report invalid formating within the .bib files, such as if an entry does not end properly when the end of the file is reached. It would then continue to index the rest of the bibliography files. It is not recommended that bibtool be used with key names that are more than 20 characters in size. If they are more than 20 characters the characters following the 20th will be truncated.