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Is there a tool that "flattens" a complicated BibTeX file?

In particular, I would like to:

  1. Expand @STRING macros, for example:

    @STRING{foo = {Bar}}
    @MISC{x, title = foo}

    @MISC{x, title = {Bar}}
  2. Expand cross references, for example:

    @INPROCEEDINGS{x, title = {A}, crossref = y}
    @PROCEEDINGS{y, title = {B}, booktitle = {B}}

    @INPROCEEDINGS{x, title = {A}, booktitle = {B}}
share|improve this question
up vote 8 down vote accepted

This can be performed by the bib2bib tool, which provides pretty flexible and reliable ways to filter/extract/expand bibtex entries. This (little known) utility is part of the bibtex2html tool suite. (Note: you have to look for the PDF documentation, the HTML documentation does not discuss bib2bib!)

For instance, to flatten a bib file, one just writes:

bib2bib --expand --expand-xrefs -ob flattened.bib original.bib   

It is also possible to specify filter and sorting options. Multiple conditions can be grouped and combined with and/or/not to extract only entries matching certain criteria.

Edit: One thing that apparently is not supported is filtering out @comment entries. These entries are, for instance, inserted by JabRef. To get rid of them just pipe the result through some regex tool. Jukka suggested perl -p0 -e 's/\s*(\@comment\{\{[^}]*\}\}\s*)+/\n\n/g' for the job.

share|improve this answer
This is almost exactly what I need; being able to flatten and filter with the same tool is great! There is one problem, though: bib2bib seems to preserve all @comment entries, no matter what I do. Even if I use the filtering options, I seem to always get all @comment entries... – Jukka Suomela Oct 12 '11 at 21:30
Right, it even adds some @comment entries. If your @comment entries are single-line only (like those added by bib2bib itself), you may just filter the resulting file through sed/grep/awk to get rid of them, e.g. grep -v "@comment" flattened.bib > nocomment.bib. – Daniel Oct 12 '11 at 21:38
You can use --no-comment to prevent bib2bib from adding any more comments, but it still preserves all existing comments. In my case I have lots of multi-line comments that are created by JabRef, and they are a bit more tricky to filter out... – Jukka Suomela Oct 12 '11 at 21:44
(Of course this is not an unsolvable problem. For example, something like perl -p0 -e 's/\s*(\@comment\{\{[^}]*\}\}\s*)+/\n\n/g' happens to work in my specific case.) – Jukka Suomela Oct 12 '11 at 22:00
Thanks Jukka, I have edited the answer accordingly. – Daniel Oct 13 '11 at 7:00

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