Recode — Notes

1 Introduction

1.1 What is Recode?

Here is version 3.6 for the Recode program and library. Hereafter, Recode means the whole package, recode means the executable program. Glance through this README file before starting configuration. Make sure you read files ABOUT-NLS and INSTALL if you are not familiar with them already.

The Recode library converts files between character sets and usages. It recognises or produces over 200 different character sets (or about 300 if combined with an iconv library) and transliterates files between almost any pair. When exact transliteration are not possible, it gets rid of offending characters or falls back on approximations. The recode program is a handy front-end to the library.

The Recode program and library have been written by François Pinard, yet it significantly reuses tabular works from Keld Simonsen. It is an evolving package, and specifications might change in future releases.

On various Unix systems, Recode is usually compiled from sources, see the Installation section below. On Linux, it often comes bundled. Recode had been ported to other popular systems. See both contrib/README and the Non-Unix ports section below, to find some more information about these.

1.2 Reports and collaboration

Send bug reports to' . A bug report is an adequate description of the problem: your input, what you expected, what you got, and why this is wrong. Diffs are welcome, but they only describe a solution, from which the problem might be uneasy to infer. If needed, submit actual data files with your report. Small data files are preferred. Big files may sometimes be necessary, but do not send them on the mailing list; rather take special arrangement with the maintainer.

Your feedback will help us to make a better and more portable package. Consider documentation errors as bugs, and report them as such. If you develop anything pertaining to Recode or have suggestions, let us know and share your findings by writing at . You may also choose to directly write at, yet be warned that such correspondence is often visible for a while through the Recode Web site.

If you feel like receiving releases and pretest announcements for the Recode package, send a message to having, in its body, a line saying:

subscribe recode-announce

If you rather want to participate actively in discussions, pretesting and development for Recode, do just as above, but this time, use::

subscribe recode-forum

Visit http://recode:8000/ for releases or pretests, and related files. In particular, button Browse gives access to a weekly mirror of the current unpackaged work files, while button Folders gives access to saved or pending correspondence.

Please do not widely redistribute releases having a letter after the version numbers, as these are meant for pretesting only, and might not be stable enough for other usages.

1.3 Development plan

My plan has long been to end the 3.x series of this package, rather aiming 4.0 as a major internal rewrite. As there is still a long way before 4.0 gets ready, and especially because some of my good collaborators insisted that I do so, there will be a Recode 3.7. That release is meant to provide a selection of user-contributed patches.

For prototyping what Recode will become and experimenting new concepts more easily, I created a subsidiary and standalone project named Recodec, meant to receive the best part of my development efforts in this particular area. Once I'll be happy with the prototype, the plan is to rewrite it from Python to C, somehow. Visit the Web pages for this Recodec project for more information and details. For now at least, new features go to Recodec only.

1.4 Notes for version 3.7-beta2

Here are a few notes related to the beta2 pre-test release for the incoming Recode 3.7. I publish it to ease later exchanges of patches with testers.

  • The name has been changed from Free recode to Recode – as "Free" was a four letter word to some people :-). recode (no capital) still names the executable program specifically, or the distribution archive itself.
  • Recode does not itself include libiconv anymore. However, it uses an external iconv library if one is available at installation time, like libiconv or the one provided within GNU libc. The -x: option to the program, or a new flag to the library recodenewouter function, inhibits the initialisation and usage of iconv.
  • The bug about loosing a few characters, here and there, when recoding big files in iconv context, seems to have been corrected. A patch for this problem has been floating around for years, but it was not solving all cases.
  • Recode installation now uses Python. In particular, it creates file build/src/iconvdecl.h from local iconv -l output. Recode testing through make check also needs what people python-devel, providing C header files for Python and distutils. The Makemore file has been merged within regular Makefiles and is not distributed separately anymore.
  • It is likely that new bugs have been introduced through the above changes. In particular, not everything is cosy on the side of release engineering. A few files are either spuriously remade, or remade late. I'm a bit surprised by the difficulty to get this right.
  • make check accepts a LIMIT= option, for limiting tests to one or a few cases. See tests/Makefile for more information.
  • PO files have been updated from the Translation Project.

1.5 Notes for version 3.7-beta1

The beta 1 pre-test release for the incoming Recode 3.7 has been made available for those needing it right away. While it solves some serious bugs and portability problems, others are meant to be addressed only in later pre-tests. In particular, none of charset or surface issues, user requests, and various suggestions appear in this pre-test, and will not either in later pretests, until all real show-stoppers are solved first. So this is in no way a candidate for a Recode 3.7 release.

The test suite is worth more comments:

  • The suite is very partial, and may not be thought as a validation suite. Before it could be used to ascertain confidence, it would need much more tests than it has already.
  • Testing is notably more speedy than it used to be. For example, the previous bigauto test, which was not run by default because it ran for too long, is now executed within the standard test suite, once in non-strict mode, and a second time in strict mode.
  • It does not use Autotest anymore, but rather a home grown test driver much inspired from the Codespeak project. The link between the test and the Recode library is established through a Pyrex interface, so you need to have python and python-devel installed first.
  • Beware that the Pyrex interface to the Recode library is only meant for testing, for now at least. While you may play with it, it would not be wise relying on it, as the specifications might change at any time.

2 Installation

2.1 Prerequisites

Simple installation of Recode requires the usual tools and facilities as those needed for most GNU packages. If not already bundled with your system, you also need to pre-install Python, version 2.2 or better. You may get it from:

It is also convenient to have some iconv library already present on your system, this much extends Recode capabilities, especially in the area of Asiatic character sets. GNU libc, as found on Linux systems and a few others, already has such an iconv library. Otherwise, you might consider pre-installing the portable libiconv, written by Bruno Haible. You may get it from:

2.2 Getting a release

Source files and various distributions (either latest, prestest, or archive) are available through:

File timestamps after checkout may trigger Make difficulties. As a way to avoid these, from the top level of the distribution, execute sh before configuring. If you miss either sh or GNU touch, try python instead.

2.3 Configure options

Once you have an unpacked distribution, see files:

File name Description
ABOUT-NLS how to customise this program to your language
COPYING copying conditions for the program
COPYING.LIB copying conditions for the library
INSTALL compilation and installation instructions
NEWS major changes in the current release
THANKS partial list of contributors

Besides those configure options documented in files INSTALL and ABOUT-NLS, a few extra options may be accepted after ./configure:

  • Options –disable-shared or –disable-static

    to inhibit the building of shared libraries or static libraries; the default is to always build static libraries, and to attempt building shared libraries if there is some known recipe for this.

  • Option –with-gnu-ld

    to force the assumption that the C compiler uses GNU ld.

  • Option –with-dmalloc

    to trigger a debugging feature for looking at memory management problems, it pre-requires Gray Watson's package, which is available as .

2.4 Maintenance tools

For simple modifications to Recode, you should not need special tools beyond those usual for installing GNU packages. However, if you modify any .l source file, Python and Flex are both needed for remaking merged.c.

For more comprehensive modifications, you might need more tools. If not done already, make sure you have a copy of the packages listed in the following table. You may also choose to establish a link in your build doc/ directory, as explained within doc/Makemore.

Package name Current Minimum Install after
autoconf 2.61 2.12 m4
automake 1.10 1.9 Perl
Flex 2.5.33 2.5.4a
gettext 0.16 0.16
Help2man 1.36 1.020 Perl
libtool 1.5.24 1.3.4
m4 1.4.10 1.4n
Make 3.81
Perl 5.8.8 5.005.03
Python 2.5.1 2.2
tar 1.17 1.12
wget 1.10.2

The current version numbers just happen to be those used for development, it is often likely that older versions would work just as well. The minimum version numbers were once acceptable, they might not be anymore, this has not been verified; any updating information is welcome!

2.5 Installation hints

Here are a few hints which might help installing Recode on some systems. Many may be applied by temporary presetting environment variables while calling ./configure. File INSTALL explains this.

  • Compilation time

    Some C compilers, like Apollo's, have a hard time compiling merged.c. If this is your case, avoid compiler optimisation. From within the Bourne shell, you may use:

    CFLAGS= ./configure

    But if you want to give a real hard time to your C optimiser on merged.c, to get code that runs only a bit faster, merely try:

  • Smallish systems

    For 80286 based systems (do some still exist?!), it has been reported that some compilers generate wrong code while optimising for small models. So, from within the Bourne shell, do::

    CFLAGS=-Ml LDFLAGS=-Ml ./configure

    to force large memory model. For 80286 Xenix compiler, the last time it was tried a while ago, one ought to use::

    CFLAGS='-Ml -F2000' LDFLAGS=-Ml ./configure

    Other systems have poor pipe*/*popen support or thrash heavily when processes fork. In this case, just before doing make, edit config.h and ensure HAVEPIPE is not defined.

3 External pointers

3.1 Documentation

  • IETF references
  • Various references
  • Recode specific
    • ETL presentation In 1999, the organisers of the m17n99 conference in Tsukuba, Japan, were kind enough to invite me. This has been for me a fabulous trip and experience, and I met many extraordinary people in there. At the conference, I presented the Translation Project, and Recode. The Recode presentation slides are available.

3.2 Programs

This comprehensive charset converter library revolves around Unicode, and support Asian encodings among many others. Even Recode uses it!

Bruno Haible <>

Here is the main recoding tool from the Plan9 project.
This GUI editor handles many encodings, among which UTF-8. It also installs uniconv, a recoding program, and uniprint, a printing tool.

Gaspar Sinai <>, 1999-01.

These 6x13 fonts, covering Unicode characters besides the Asian sets, merely replace the Linux fixed 6x13 font. Works nicely with yudit.

Markus Kuhn <>, 1998-11.

This charset converter is oriented towards SGML text manipulation. It may be freely downloaded for non-commercial, non-military use from:

Pointer given by Jean Véronis <>, 1996-06.

This quite nice SGML structure analyser contains internal C++ modules for handling many charsets.

James Clark <>

This program is able to generate interpreted character dumps, but properly embedded within complete C header files.

Jörg Heitkötter <>, 1997-11.

This wrapper provides Recode functionality to Python programs.

Andreas Jung <> Also see:

3.3 Non-Unix ports

Please if you are aware of various ports to non-Unix systems not listed here, or for corrections. Please provide the goal system, a complete and stable URL, the maintainer name and address, the Recode version used as a base, and your comments.