ptx

Generate index with line references

$ ptx -r [file]

$ ptx -A [file]

$ ptx -w [80] [file]

$ ptx -o [filter_file] [file]

$ ptx -G [file]

ptx [-A] [-r] [-w width] [-o file] [-G] [inputfile_]

ptx produces a permuted index (also known as KWIC - Key Word In Context) from text files. Each significant word appears as an index entry with surrounding context, allowing readers to locate topics by any word.
The output shows each word centered with its surrounding context, useful for creating concordances or keyword indexes for documentation.

-A, --auto-reference

Generate automatic index references

Use first field as index reference

Output line width in columns

Read list of words to index

Read list of words to ignore

SYSV-compatible behavior

Output format designed for old terminals. May need post-processing for modern use. Word filtering requires separate file. Large files produce extensive output.

ptx is a traditional Unix text processing tool, part of GNU coreutils. Permuted indexes were important for printed documentation before full-text search became common.

sort(1), grep(1), awk(1)