cod-tools is an open-source collection of command line scripts for handling of CIF files. The package is developed by the team of Crystallography Open Database developers. Detailed information for the usage of each individual script from the package can be obtained by invoking commands with --help and --usage command line options. For example:

cif_filter --help
cif_filter --usage
  • cif_cod_check – parse a CIF file, check if certain data values match COD requirements and IUCr data validation criteria (Version: 2000.06.09, or

  • cif_cod_deposit – deposit CIFs into COD database using CGI deposition interface.

  • cif_cod_numbers – find COD numbers for the .cif files in given directories of file lists.

  • cif_correct_tags – correct misspelled tags in a CIF file.

  • cif_filter – parse a CIF file and print out essential data values in the CIF format, the COD CIF style.

    This script has also many capabilities – it can restore space group symbols from symmetry operators (consulting predefined tables), parse and tidy-up _chemical_formula_sum, compute cell volume, exclude unknown or "empty" tags, and add specified bibliography data.

  • cif_fix_values – correct temperature values which have units specified or convert between Celsius degrees and Kelvins. Changes 'room/ambiante temperature' to the appropriate numeric value. Fixes other undefined values (no, not measured, etc.) to '?' symbol. Determine a report about changes made into standard I/O streams.

    Fixes enumeration values in CIF file against CIF dictionaries.

  • cif_mark_disorder – marks disorder in CIF files judging by distance and occupancy.

  • cif_molecule – restores molecules from a CIF file.

  • cif_select – read CIFs and print out selected tags with their values.

  • cif_split – split CIF files into separate files with one data_ section each.

    This script parses given CIF files to separate the data blocks, so is capable of splitting non-correctly formatted and nested CIF files.

  • cif_split_primitive – split CIF files into separate files with one data_ section each.

    This is a very naive and primitive version of the splitter, which expects each data_... section to start on a new line. It may fail on some CIF files that do not follow such convention. For splitting of any correctly formatted CIF files, one must do full CIF parsing using CIF grammar and tokenisation of the file.


Currently cod-tools package is distributed via source code only. To prepare the package for usage one has to follow these steps:

  • Get the source:

    • Version 2.1 can be downloaded as tbz2 archive from here. To unpack one can execute:

          bzip2 --decompress cod-tools-2.1.tbz2
          tar -xvf cod-tools-2.1.tar
          mv cod-tools-2.1 cod-tools
    • The latest revision (as well as any other) can be retrieved from the Subversion repository:

          svn co svn:// cod-tools
  • Install the dependencies:

      bash -e cod-tools/dependencies/Ubuntu-16.04/

    Note: the dependency installer is written for Ubuntu 16.04, but works fine on some older or newer Ubuntu as well as Debian distributions.

  • Build and test:

      make -C cod-tools
  • Set up:

    • Install:

          make -C cod-tools install

      This command will place executables and libraries in standard locations under /usr where they should be automatically located by the most of Unix-like operating systems.

    • Prepare the environment for usage without installing. Described below are two methods of setting the environment for cod-tools as of source revision 3393 or newer:

      • Using Bash:

            export PATH=${CODTOOLS_SRC}/scripts:${PATH}
            export PERL5LIB=${CODTOOLS_SRC}/src/lib/perl5:${PERL5LIB}

        These commands can be pasted to ~/.bashrc file, which is sourced automatically on the opening of a new shell.

      • Using modulefile:

            module-whatis    loads the cod-tools environment
            set             CODTOOLS_SRC    ~/src/cod-tools
            prepend-path    PATH            ${CODTOOLS_SRC}/scripts
            prepend-path    PERL5LIB        ${CODTOOLS_SRC}/src/lib/perl5


  • Fix a syntactically incorrect structure:

    Some simple common CIF syntax errors can be fixed automatically using cif_filter with --fix-syntax option. For example, such structure:

      _publ_section_title "Runaway quote
      C 0 0 0

    can be fixed (provided it's stored in test.cif):

      cif_filter --fix test.cif

    Obtained structure:

      _publ_section_title              'Runaway quote'
      C 0 0 0

    A warning message tells what was done:

      cif_filter: test.cif(2) data_broken: WARNING, double-quoted string is missing a closing quote -- fixed.
    • cif_filter is the name of the used script;
    • test.cif is the name of the CIF file;
    • 2 is the number of a line in the file;
    • data_broken is the CIF data block name;
    • WARNING is the level of severity;
    • rest is the message text.
  • Fetch a structure from Web, filter and fix it, restore the crystal contents and calculate summary formulae per each compound in a crystal:

      curl --silent \
          | cif_filter \
          | cif_fix_values \
          | cif_molecule \
          | cif_cell_contents --use-attached-hydrogens

    Obtained result:

      C9 H14 N
      C10 H6 O6 S2
      H2 O

    As well as a warning message:

      cif_molecule: - data_2231955: WARNING, multiplicity ratios are given instead of multiplicities for 39 atoms -- taking calculated values.
  • Fetch a structure from Web and mark alternative atoms sharing same site:

      curl --silent \
          | cif_mark_disorder \
          | cif_select --cif --tag _atom_site_label

    Obtained result:

      Pb Pb1 0.5000 0.0000 0.2500 0.0213(13) Uani d S 1 4 . .
      Mo Mo2 0.0000 0.0000 0.0000 0.022(4) Uani d S 1 4 . .
      Pb Pb3 0.5000 0.5000 0.0000 0.025(2) Uani d SP 0.881(8) 4 A 1
      Mo Mo3 0.5000 0.5000 0.0000 0.025(2) Uani d SP 0.119(8) 4 A 2
      Mo Mo1 0.0000 0.5000 0.2500 0.018(3) Uani d S 1 4 . .
      O O1 0.2344(13) -0.1372(14) 0.0806(6) 0.0302(17) Uani d . 1 1 . .
      O O2 0.2338(14) 0.3648(14) 0.1697(6) 0.0307(17) Uani d . 1 1 . .

    As well as output messages:

      cif_mark_disorder: - data_2018107: NOTE, atoms 'Mo3', 'Pb3' were marked as alternatives.
      cif_mark_disorder: - data_2018107: NOTE, 1 site(s) were marked as disorder assemblies.

    Note: atoms Mo3 and Pb3 share the same site, as can be found out by checking their coordinates. Moreover, sum of their occupancies is close to 1. In the original CIF file these sites have both _atom_site_disorder_assembly and _atom_site_disorder_group set to '.'.


cod-tools is licensed under GPL2 free software license.


If you use cod-tools in your research, please cite the following papers:

  • Merkys, A., Vaitkus, A., Butkus, J., Okulič-Kazarinas, M., Kairys, V. & Gražulis, S. (2016) "COD::CIF::Parser: an error-correcting CIF parser for the Perl language". Journal of Applied Crystallography 49. (BibTeX, EndNote/Refer, plain text)

  • Gražulis, S., Merkys, A., Vaitkus, A. & Okulič-Kazarinas, M. (2015) "Computing stoichiometric molecular composition from crystal structures". Journal of Applied Crystallography 48, 85-91. (BibTeX, EndNote/Refer, plain text)