BibTeX files are typically manually maintained and thus often contain inconsistencies, mistakes, or are missing information. betterbib helps maintaining your BibTeX files by comparing them with online sources and correcting whatever entries are found faulty.
betterbib in.bib out.bib
All of the following tools can read from standard input and write to standard output, so you can concatenate them to get exactly what you want. For example, the above betterbib command is equivalent to
betterbib-sync in.bib | betterbib-journal-abbrev | betterbib-format -b - out.bib
betterbib is available from the Python Package Index, so simply do
pip install betterbib