indxbib

indxbib [-o output] [-t title] [-V] [-v] [file ...]

-o output
    Direct index output to output file (default: first file.i)

-t title
    Set title as the index title line (default: first filename)

-V
    Print version information and exit

-v
    Enable verbose mode, printing progress and warnings

indxbib is a utility from the groff package that generates an index file for bibliography databases in the refer(1) format. This index enables fast searching with lookbib(1), which otherwise would scan entire files linearly.

It processes one or more input files (or stdin if none specified), extracting citation keys—unique labels like %A or %K fields from refer entries. Keys are sorted lexicographically and written to an output index file, typically named after the first input file with .i appended.

Common workflow: prepare bibliography in refer format, run indxbib to index it, then use lookbib for queries during document preparation with refer(1) in troff/nroff pipelines. For example, large publication lists benefit from indexing to avoid performance issues.

indxbib handles multiple files by concatenating keys uniquely. It ignores malformed entries, printing warnings in verbose mode. The resulting index is compact yet efficient for prefix-based lookups, supporting tools in traditional Unix typesetting.

Index files grow large for extensive bibliographies; ignores invalid refer entries without -v; stdin input uses stdin.i by default.

indxbib -o papers.i papers.bib
lookbib -db papers.i "machine learning"

Expects refer-style entries starting with %-fields; see refer(1) for details.

Originated in Version 7 Unix (1979) as part of AT&T troff tools; maintained in GNU groff since 1990s for modern systems.

lookbib(1), refer(1), lkbib(1), roff(7)