$ gemmi cif2json -h
Usage:
 gemmi cif2json [options] INPUT_FILE OUTPUT_FILE

Convert CIF file (any CIF files, including mmCIF) to JSON.
The output can be COMCIFS CIF-JSON (-c), mmJSON (-m),
or a custom JSON flavor (default).

General options:
  -h, --help             Print usage and exit.
  -V, --version          Print version and exit.
  -v, --verbose          Verbose output.

JSON output options:
  -c, --comcifs          Conform to the COMCIFS CIF-JSON standard draft.
  -m, --mmjson           Compatible with mmJSON from PDBj.
  --bare-tags            Output tags without the first underscore.
  --numb=quote|nosu|mix  Convert the CIF numb type to one of:
                           quote - string in quotes,
                           nosu - number without s.u.,
                           mix (default) - quote only numbs with s.u.
  --dot=STRING           JSON representation of CIF's '.' (default: null).

Modifications:
  --skip-category=CAT    Do not output tags starting with _CAT
  --sort                 Sort tags in alphabetical order.

When output file is -, write to standard output.