GNU gettext utilities: 13. The Maintainer's View

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# 13. The Maintainer's View

The maintainer of a package has many responsibilities. One of them is ensuring that the package will install easily on many platforms, and that the magic we described earlier (see section The User's View) will work for installers and end users.

Of course, there are many possible ways by which GNU `gettext` might be integrated in a distribution, and this chapter does not cover them in all generality. Instead, it details one possible approach which is especially adequate for many free software distributions following GNU standards, or even better, Gnits standards, because GNU `gettext` is purposely for helping the internationalization of the whole GNU project, and as many other good free packages as possible. So, the maintainer's view presented here presumes that the package already has a ‘`configure.ac`’ file and uses GNU Autoconf.

Nevertheless, GNU `gettext` may surely be useful for free packages not following GNU standards and conventions, but the maintainers of such packages might have to show imagination and initiative in organizing their distributions so `gettext` work for them in all situations. There are surely many, out there.

Even if `gettext` methods are now stabilizing, slight adjustments might be needed between successive `gettext` versions, so you should ideally revise this chapter in subsequent releases, looking for changes.

## 13.1 Flat or Non-Flat Directory Structures

Some free software packages are distributed as `tar` files which unpack in a single directory, these are said to be flat distributions. Other free software packages have a one level hierarchy of subdirectories, using for example a subdirectory named ‘`doc/`’ for the Texinfo manual and man pages, another called ‘`lib/`’ for holding functions meant to replace or complement C libraries, and a subdirectory ‘`src/`’ for holding the proper sources for the package. These other distributions are said to be non-flat.

We cannot say much about flat distributions. A flat directory structure has the disadvantage of increasing the difficulty of updating to a new version of GNU `gettext`. Also, if you have many PO files, this could somewhat pollute your single directory. Also, GNU `gettext`'s libintl sources consist of C sources, shell scripts, `sed` scripts and complicated Makefile rules, which don't fit well into an existing flat structure. For these reasons, we recommend to use non-flat approach in this case as well.

Maybe because GNU `gettext` itself has a non-flat structure, we have more experience with this approach, and this is what will be described in the remaining of this chapter. Some maintainers might use this as an opportunity to unflatten their package structure.

## 13.2 Prerequisite Works

There are some works which are required for using GNU `gettext` in one of your package. These works have some kind of generality that escape the point by point descriptions used in the remainder of this chapter. So, we describe them here.

- Before attempting to use `gettextize` you should install some other packages first. Ensure that recent versions of GNU `m4`, GNU Autoconf and GNU `gettext` are already installed at your site, and if not, proceed to do this first. If you get to install these things, beware that GNU `m4` must be fully installed before GNU Autoconf is even configured.

  To further ease the task of a package maintainer the `automake` package was designed and implemented. GNU `gettext` now uses this tool and the ‘`Makefile`’ in the ‘`po/`’ directory therefore knows about all the goals necessary for using `automake`.

  Those four packages are only needed by you, as a maintainer; the installers of your own package and end users do not really need any of GNU `m4`, GNU Autoconf, GNU `gettext`, or GNU `automake` for successfully installing and running your package, with messages properly translated. But this is not completely true if you provide internationalized shell scripts within your own package: GNU `gettext` shall then be installed at the user site if the end users want to see the translation of shell script messages.

- Your package should use Autoconf and have a ‘`configure.ac`’ or ‘`configure.in`’ file. If it does not, you have to learn how. The Autoconf documentation is quite well written, it is a good idea that you print it and get familiar with it.
- Your C sources should have already been modified according to instructions given earlier in this manual. See section Preparing Program Sources.
- Your ‘`po/`’ directory should receive all PO files submitted to you by the translator teams, each having ‘`ll.po`’ as a name. This is not usually easy to get translation work done before your package gets internationalized and available! Since the cycle has to start somewhere, the easiest for the maintainer is to start with absolutely no PO files, and wait until various translator teams get interested in your package, and submit PO files.

It is worth adding here a few words about how the maintainer should ideally behave with PO files submissions. As a maintainer, your role is to authenticate the origin of the submission as being the representative of the appropriate translating teams of the Translation Project (forward the submission to ‘`coordinator@translationproject.org`’ in case of doubt), to ensure that the PO file format is not severely broken and does not prevent successful installation, and for the rest, to merely put these PO files in ‘`po/`’ for distribution.

As a maintainer, you do not have to take on your shoulders the responsibility of checking if the translations are adequate or complete, and should avoid diving into linguistic matters. Translation teams drive themselves and are fully responsible of their linguistic choices for the Translation Project. Keep in mind that translator teams are not driven by maintainers. You can help by carefully redirecting all communications and reports from users about linguistic matters to the appropriate translation team, or explain users how to reach or join their team.

Maintainers should never ever apply PO file bug reports themselves, short-cutting translation teams. If some translator has difficulty to get some of her points through her team, it should not be an option for her to directly negotiate translations with maintainers. Teams ought to settle their problems themselves, if any. If you, as a maintainer, ever think there is a real problem with a team, please never try to solve a team's problem on your own.

## 13.3 Invoking the `gettextize` Program

The `gettextize` program is an interactive tool that helps the maintainer of a package internationalized through GNU `gettext`. It is used for two purposes:

- As a wizard, when a package is modified to use GNU `gettext` for the first time.
- As a migration tool, for upgrading the GNU `gettext` support in a package from a previous to a newer version of GNU `gettext`.

This program performs the following tasks:

- It copies into the package some files that are consistently and identically needed in every package internationalized through GNU `gettext`.
- It performs as many of the tasks mentioned in the next section Files You Must Create or Alter as can be performed automatically.
- It removes obsolete files and idioms used for previous GNU `gettext` versions to the form recommended for the current GNU `gettext` version.
- It prints a summary of the tasks that ought to be done manually and could not be done automatically by `gettextize`.

It can be invoked as follows:

    gettextize [ option… ] [ directory ]

and accepts the following options:

‘`-f`’
‘`--force`’

  Force replacement of files which already exist.

‘`--po-dir=dir`’

  Specify a directory containing PO files. Such a directory contains the translations into various languages of a particular POT file. This option can be specified multiple times, once for each translation domain. If it is not specified, the directory named ‘`po/`’ is updated.

‘`--no-changelog`’

  Don't update or create ChangeLog files. By default, `gettextize` logs all changes (file additions, modifications and removals) in a file called ‘`ChangeLog`’ in each affected directory.

‘`--symlink`’

  Make symbolic links instead of copying the needed files. This can be useful to save a few kilobytes of disk space, but it requires extra effort to create self-contained tarballs, it may disturb some mechanism the maintainer applies to the sources, and it is likely to introduce bugs when a newer version of `gettext` is installed on the system.

‘`-n`’
‘`--dry-run`’

  Print modifications but don't perform them. All actions that `gettextize` would normally execute are inhibited and instead only listed on standard output.

‘`--help`’

  Display this help and exit.

‘`--version`’

  Output version information and exit.

If directory is given, this is the top level directory of a package to prepare for using GNU `gettext`. If not given, it is assumed that the current directory is the top level directory of such a package.

The program `gettextize` provides the following files. However, no existing file will be replaced unless the option `--force` (`-f`) is specified.

1. The ‘`ABOUT-NLS`’ file is copied in the main directory of your package, the one being at the top level. This file contains a reference to the GNU gettext documentation. It also avoids an error from Automake in packages that use the Automake option ‘`gnu`’ or ‘`gnits`’: “error: required file './ABOUT-NLS' not found”.
2. A ‘`po/`’ directory is created for eventually holding all translation files, but initially only containing the file ‘`po/Makefile.in.in`’ from the GNU `gettext` distribution (beware the double ‘`.in`’ in the file name) and a few auxiliary files. If the ‘`po/`’ directory already exists, it will be preserved along with the files it contains, and only ‘`Makefile.in.in`’ and the auxiliary files will be overwritten.

   If ‘`--po-dir`’ has been specified, this holds for every directory specified through ‘`--po-dir`’, instead of ‘`po/`’.

3. The file ‘`config.rpath`’ is copied into the directory containing configuration support files. It is needed by the `AM_GNU_GETTEXT` autoconf macro.
4. Only if the project is using GNU `automake`: A set of `autoconf` macro files is copied into the package's `autoconf` macro repository, usually in a directory called ‘`m4/`’.

If your site support symbolic links, `gettextize` will not actually copy the files into your package, but establish symbolic links instead. This avoids duplicating the disk space needed in all packages. Merely using the ‘`-h`’ option while creating the `tar` archive of your distribution will resolve each link by an actual copy in the distribution archive. So, to insist, you really should use ‘`-h`’ option with `tar` within your `dist` goal of your main ‘`Makefile.in`’.

Furthermore, `gettextize` will update all ‘`Makefile.am`’ files in each affected directory, as well as the top level ‘`configure.ac`’ or ‘`configure.in`’ file.

It is interesting to understand that most new files for supporting GNU `gettext` facilities in one package go in ‘`po/`’ and ‘`m4/`’ subdirectories. Still, these directories will mostly contain package dependent files.

The `gettextize` program makes backup files for all files it replaces or changes, and also write ChangeLog entries about these changes. This way, the careful maintainer can check after running `gettextize` whether its changes are acceptable to him, and possibly adjust them. An exception to this rule is the ‘`intl/`’ directory, which is removed as a whole if it still existed.

It is important to understand that `gettextize` can not do the entire job of adapting a package for using GNU `gettext`. The amount of remaining work depends on whether the package uses GNU `automake` or not. But in any case, the maintainer should still read the section Files You Must Create or Alter after invoking `gettextize`.

In particular, if after using ‘`gettexize`’, you get an error ‘`AC_COMPILE_IFELSE was called before AC_GNU_SOURCE`’ or ‘`AC_RUN_IFELSE was called before AC_GNU_SOURCE`’, you can fix it by modifying ‘`configure.ac`’, as described in ‘`configure.ac`’ at top level.

It is also important to understand that `gettextize` is not part of the GNU build system, in the sense that it should not be invoked automatically, and not be invoked by someone who doesn't assume the responsibilities of a package maintainer. For the latter purpose, a separate tool is provided, see Invoking the `autopoint` Program.

## 13.4 Files You Must Create or Alter

Besides files which are automatically added through `gettextize`, there are many files needing revision for properly interacting with GNU `gettext`. If you are closely following GNU standards for Makefile engineering and auto-configuration, the adaptations should be easier to achieve. Here is a point by point description of the changes needed in each.

So, here comes a list of files, each one followed by a description of all alterations it needs. Many examples are taken out from the GNU `gettext` 0.22.2 distribution itself, or from the GNU `hello` distribution (https://www.gnu.org/software/hello). You may indeed refer to the source code of the GNU `gettext` and GNU `hello` packages, as they are intended to be good examples for using GNU gettext functionality.

### 13.4.1 ‘`POTFILES.in`’ in ‘`po/`’

The ‘`po/`’ directory should receive a file named ‘`POTFILES.in`’. This file tells which files, among all program sources, have marked strings needing translation. Here is an example of such a file:

    # List of source files containing translatable strings.
    # Copyright (C) 1995 Free Software Foundation, Inc.

    # Common library files
    lib/error.c
    lib/getopt.c
    lib/xmalloc.c

    # Package source files
    src/gettext.c
    src/msgfmt.c
    src/xgettext.c

Hash-marked comments and white lines are ignored. All other lines list those source files containing strings marked for translation (see section How Marks Appear in Sources), in a notation relative to the top level of your whole distribution, rather than the location of the ‘`POTFILES.in`’ file itself.

When a C file is automatically generated by a tool, like `flex` or `bison`, that doesn't introduce translatable strings by itself, it is recommended to list in ‘`po/POTFILES.in`’ the real source file (ending in ‘`.l`’ in the case of `flex`, or in ‘`.y`’ in the case of `bison`), not the generated C file.

### 13.4.2 ‘`LINGUAS`’ in ‘`po/`’

The ‘`po/`’ directory should also receive a file named ‘`LINGUAS`’. This file contains the list of available translations. It is a whitespace separated list. Hash-marked comments and white lines are ignored. Here is an example file:

    # Set of available languages.
    de fr

This example means that German and French PO files are available, so that these languages are currently supported by your package. If you want to further restrict, at installation time, the set of installed languages, this should not be done by modifying the ‘`LINGUAS`’ file, but rather by using the `LINGUAS` environment variable (see section The Installer's and Distributor's View).

It is recommended that you add the "languages" ‘`en@quot`’ and ‘`en@boldquot`’ to the `LINGUAS` file. `en@quot` is a variant of English message catalogs (`en`) which uses real quotation marks instead of the ugly looking asymmetric ASCII substitutes ‘```’ and ‘`'`’. `en@boldquot` is a variant of `en@quot` that additionally outputs quoted pieces of text in a bold font, when used in a terminal emulator which supports the VT100 escape sequences (such as `xterm` or the Linux console, but not Emacs in `M-x shell` mode).

These extra message catalogs ‘`en@quot`’ and ‘`en@boldquot`’ are constructed automatically, not by translators; to support them, you need the files ‘`Rules-quot`’, ‘`quot.sed`’, ‘`boldquot.sed`’, ‘`en@quot.header`’, ‘`en@boldquot.header`’, ‘`insert-header.sin`’ in the ‘`po/`’ directory. You can copy them from GNU gettext's ‘`po/`’ directory; they are also installed by running `gettextize`.

### 13.4.3 ‘`Makevars`’ in ‘`po/`’

The ‘`po/`’ directory also has a file named ‘`Makevars`’. It contains variables that are specific to your project. ‘`po/Makevars`’ gets inserted into the ‘`po/Makefile`’ when the latter is created. The variables thus take effect when the POT file is created or updated, and when the message catalogs get installed.

The first three variables can be left unmodified if your package has a single message domain and, accordingly, a single ‘`po/`’ directory. Only packages which have multiple ‘`po/`’ directories at different locations need to adjust the three first variables defined in ‘`Makevars`’.

As an alternative to the `XGETTEXT_OPTIONS` variable, it is also possible to specify `xgettext` options through the `AM_XGETTEXT_OPTION` autoconf macro. See AM_XGETTEXT_OPTION in ‘`po.m4`’.

### 13.4.4 Extending ‘`Makefile`’ in ‘`po/`’

All files called ‘`Rules-*`’ in the ‘`po/`’ directory get appended to the ‘`po/Makefile`’ when it is created. They present an opportunity to add rules for special PO files to the Makefile, without needing to mess with ‘`po/Makefile.in.in`’.

GNU gettext comes with a ‘`Rules-quot`’ file, containing rules for building catalogs ‘`en@quot.po`’ and ‘`en@boldquot.po`’. The effect of ‘`en@quot.po`’ is that people who set their `LANGUAGE` environment variable to ‘`en@quot`’ will get messages with proper looking symmetric Unicode quotation marks instead of abusing the ASCII grave accent and the ASCII apostrophe for indicating quotations. To enable this catalog, simply add `en@quot` to the ‘`po/LINGUAS`’ file. The effect of ‘`en@boldquot.po`’ is that people who set `LANGUAGE` to ‘`en@boldquot`’ will get not only proper quotation marks, but also the quoted text will be shown in a bold font on terminals and consoles. This catalog is useful only for command-line programs, not GUI programs. To enable it, similarly add `en@boldquot` to the ‘`po/LINGUAS`’ file.

Similarly, you can create rules for building message catalogs for the ‘`sr@latin`’ locale – Serbian written with the Latin alphabet – from those for the ‘`sr`’ locale – Serbian written with Cyrillic letters. See Invoking the `msgfilter` Program.

### 13.4.5 ‘`configure.ac`’ at top level

‘`configure.ac`’ or ‘`configure.in`’ - this is the source from which `autoconf` generates the ‘`configure`’ script.

1. Declare the package and version.

   This is done by a set of lines like these:

       PACKAGE=gettext
       VERSION=0.22.2
       AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
       AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
       AC_SUBST(PACKAGE)
       AC_SUBST(VERSION)

   or, if you are using GNU `automake`, by a line like this:

       AM_INIT_AUTOMAKE(gettext, 0.22.2)

   Of course, you replace ‘`gettext`’ with the name of your package, and ‘`0.22.2`’ by its version numbers, exactly as they should appear in the packaged `tar` file name of your distribution (‘`gettext-0.22.2.tar.gz`’, here).

2. Check for internationalization support.

   Here is the main `m4` macro for triggering internationalization support. Just add this line to ‘`configure.ac`’:

       AM_GNU_GETTEXT([external])

   This call is purposely simple, even if it generates a lot of configure time checking and actions.

3. Have output files created.

   The `AC_OUTPUT` directive, at the end of your ‘`configure.ac`’ file, needs to be modified in two ways:

       AC_OUTPUT([existing configuration files po/Makefile.in],
       [existing additional actions])

   The modification to the first argument to `AC_OUTPUT` asks for substitution in the ‘`po/`’ directory. Note the ‘`.in`’ suffix used for ‘`po/`’ only. This is because the distributed file is really ‘`po/Makefile.in.in`’.

### 13.4.6 ‘`config.guess`’, ‘`config.sub`’ at top level

You need to add the GNU ‘`config.guess`’ and ‘`config.sub`’ files to your distribution. They are needed because the `AM_ICONV` macro contains knowledge about specific platforms and therefore needs to identify the platform.

You can obtain the newest version of ‘`config.guess`’ and ‘`config.sub`’ from the ‘`config`’ project at ‘`https://savannah.gnu.org/`’. The commands to fetch them are

    $ wget -O config.guess 'https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD'
    $ wget -O config.sub 'https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD'

Less recent versions are also contained in the GNU `automake` and GNU `libtool` packages.

Normally, ‘`config.guess`’ and ‘`config.sub`’ are put at the top level of a distribution. But it is also possible to put them in a subdirectory, altogether with other configuration support files like ‘`install-sh`’, ‘`ltconfig`’, ‘`ltmain.sh`’ or ‘`missing`’. All you need to do, other than moving the files, is to add the following line to your ‘`configure.ac`’.

    AC_CONFIG_AUX_DIR([subdir])

### 13.4.7 ‘`mkinstalldirs`’ at top level

With earlier versions of GNU gettext, you needed to add the GNU ‘`mkinstalldirs`’ script to your distribution. This is not needed any more. You can remove it.

### 13.4.8 ‘`aclocal.m4`’ at top level

If you do not have an ‘`aclocal.m4`’ file in your distribution, the simplest is to concatenate the files ‘`build-to-host.m4`’, ‘`gettext.m4`’, ‘`host-cpu-c-abi.m4`’, ‘`intlmacosx.m4`’, ‘`iconv.m4`’, ‘`lib-ld.m4`’, ‘`lib-link.m4`’, ‘`lib-prefix.m4`’, ‘`nls.m4`’, ‘`po.m4`’, ‘`progtest.m4`’ from GNU `gettext`'s ‘`m4/`’ directory into a single file.

If you already have an ‘`aclocal.m4`’ file, then you will have to merge the said macro files into your ‘`aclocal.m4`’. Note that if you are upgrading from a previous release of GNU `gettext`, you should most probably replace the macros (`AM_GNU_GETTEXT`, etc.), as they usually change a little from one release of GNU `gettext` to the next. Their contents may vary as we get more experience with strange systems out there.

You should be using GNU `automake` 1.9 or newer. With it, you need to copy the files ‘`build-to-host.m4`’, ‘`gettext.m4`’, ‘`host-cpu-c-abi.m4`’, ‘`intlmacosx.m4`’, ‘`iconv.m4`’, ‘`lib-ld.m4`’, ‘`lib-link.m4`’, ‘`lib-prefix.m4`’, ‘`nls.m4`’, ‘`po.m4`’, ‘`progtest.m4`’ from GNU `gettext`'s ‘`m4/`’ directory to a subdirectory named ‘`m4/`’ and add the line

    ACLOCAL_AMFLAGS = -I m4

to your top level ‘`Makefile.am`’.

If you are using GNU `automake` 1.10 or newer, it is even easier: Add the line

    ACLOCAL_AMFLAGS = --install -I m4

to your top level ‘`Makefile.am`’, and run ‘`aclocal --install -I m4`’. This will copy the needed files to the ‘`m4/`’ subdirectory automatically, before updating ‘`aclocal.m4`’.

These macros check for the internationalization support functions and related informations. Hopefully, once stabilized, these macros might be integrated in the standard Autoconf set, because this piece of `m4` code will be the same for all projects using GNU `gettext`.

### 13.4.9 ‘`config.h.in`’ at top level

The include file template that holds the C macros to be defined by `configure` is usually called ‘`config.h.in`’ and may be maintained either manually or automatically.

If it is maintained automatically, by use of the ‘`autoheader`’ program, you need to do nothing about it. This is the case in particular if you are using GNU `automake`.

If it is maintained manually, you can get away by adding the following lines to ‘`config.h.in`’:

    /* Define to 1 if translation of program messages to the user's
       native language is requested. */
    #undef ENABLE_NLS

### 13.4.10 ‘`Makefile.in`’ at top level

Here are a few modifications you need to make to your main, top-level ‘`Makefile.in`’ file.

1. Add the following lines near the beginning of your ‘`Makefile.in`’, so the ‘`dist:`’ goal will work properly (as explained further down):

       PACKAGE = @PACKAGE@
       VERSION = @VERSION@

2. Wherever you process subdirectories in your ‘`Makefile.in`’, be sure you also process the subdirectory ‘`po`’. Special rules in the ‘`Makefiles`’ take care for the case where no internationalization is wanted.

   If you are using Makefiles, either generated by automake, or hand-written so they carefully follow the GNU coding standards, the effected goals for which the new subdirectories must be handled include ‘`installdirs`’, ‘`install`’, ‘`uninstall`’, ‘`clean`’, ‘`distclean`’.

   Here is an example of a canonical order of processing. In this example, we also define `SUBDIRS` in `Makefile.in` for it to be further used in the ‘`dist:`’ goal.

       SUBDIRS = doc lib src po

3. A delicate point is the ‘`dist:`’ goal, as ‘`po/Makefile`’ will later assume that the proper directory has been set up from the main ‘`Makefile`’. Here is an example at what the ‘`dist:`’ goal might look like:

       distdir = $(PACKAGE)-$(VERSION)
       dist: Makefile
       	rm -fr $(distdir)
       	mkdir $(distdir)
       	chmod 777 $(distdir)
       	for file in $(DISTFILES); do \
       	  ln $$file $(distdir) 2>/dev/null || cp -p $$file $(distdir); \
       	done
       	for subdir in $(SUBDIRS); do \
       	  mkdir $(distdir)/$$subdir || exit 1; \
       	  chmod 777 $(distdir)/$$subdir; \
       	  (cd $$subdir && $(MAKE) $@) || exit 1; \
       	done
       	tar chozf $(distdir).tar.gz $(distdir)
       	rm -fr $(distdir)

Note that if you are using GNU `automake`, ‘`Makefile.in`’ is automatically generated from ‘`Makefile.am`’, and all needed changes to ‘`Makefile.am`’ are already made by running ‘`gettextize`’.

### 13.4.11 ‘`Makefile.in`’ in ‘`src/`’

Some of the modifications made in the main ‘`Makefile.in`’ will also be needed in the ‘`Makefile.in`’ from your package sources, which we assume here to be in the ‘`src/`’ subdirectory. Here are all the modifications needed in ‘`src/Makefile.in`’:

1. In view of the ‘`dist:`’ goal, you should have these lines near the beginning of ‘`src/Makefile.in`’:

       PACKAGE = @PACKAGE@
       VERSION = @VERSION@

2. If not done already, you should guarantee that `top_srcdir` gets defined. This will serve for `cpp` include files. Just add the line:

       top_srcdir = @top_srcdir@

3. You might also want to define `subdir` as ‘`src`’, later allowing for almost uniform ‘`dist:`’ goals in all your ‘`Makefile.in`’. At list, the ‘`dist:`’ goal below assume that you used:

       subdir = src

4. The `main` function of your program will normally call `bindtextdomain` (see see section Triggering `gettext` Operations), like this:

       bindtextdomain (PACKAGE, LOCALEDIR);
       textdomain (PACKAGE);

   On native Windows platforms, the `main` function may call `wbindtextdomain` instead of `bindtextdomain`.

   To make LOCALEDIR known to the program, add the following lines to ‘`Makefile.in`’:

       datadir = @datadir@
       datarootdir= @datarootdir@
       localedir = @localedir@
       DEFS = -DLOCALEDIR=$(localedir_c_make) @DEFS@

   `$(localedir_c_make)` expands to the value of `localedir`, in C syntax, escaped for use in a `Makefile`. Note that `@datadir@` defaults to ‘`$(prefix)/share`’, and `$(localedir)` defaults to ‘`$(prefix)/share/locale`’.

5. You should ensure that the final linking will use `@LIBINTL@` or `@LTLIBINTL@` as a library. `@LIBINTL@` is for use without `libtool`, `@LTLIBINTL@` is for use with `libtool`. An easy way to achieve this is to manage that it gets into `LIBS`, like this:

       LIBS = @LIBINTL@ @LIBS@

   In most packages internationalized with GNU `gettext`, one will find a directory ‘`lib/`’ in which a library containing some helper functions will be build. (You need at least the few functions which the GNU `gettext` Library itself needs.) However some of the functions in the ‘`lib/`’ also give messages to the user which of course should be translated, too. Taking care of this, the support library (say ‘`libsupport.a`’) should be placed before `@LIBINTL@` and `@LIBS@` in the above example. So one has to write this:

       LIBS = ../lib/libsupport.a @LIBINTL@ @LIBS@

6. Your ‘`dist:`’ goal has to conform with others. Here is a reasonable definition for it:

       distdir = ../$(PACKAGE)-$(VERSION)/$(subdir)
       dist: Makefile $(DISTFILES)
       	for file in $(DISTFILES); do \
       	  ln $$file $(distdir) 2>/dev/null || cp -p $$file $(distdir) || exit 1; \
       	done

Note that if you are using GNU `automake`, ‘`Makefile.in`’ is automatically generated from ‘`Makefile.am`’, and the first three changes and the last change are not necessary. The remaining needed ‘`Makefile.am`’ modifications are the following:

1. To make LOCALEDIR known to the program, add the following to ‘`Makefile.am`’:

       <module>_CPPFLAGS = -DLOCALEDIR=$(localedir_c_make)

   for each specific module or compilation unit, or

       AM_CPPFLAGS = -DLOCALEDIR=$(localedir_c_make)

   for all modules and compilation units together.

2. To ensure that the final linking will use `@LIBINTL@` or `@LTLIBINTL@` as a library, add the following to ‘`Makefile.am`’:

       <program>_LDADD = @LIBINTL@

   for each specific program, or

       LDADD = @LIBINTL@

   for all programs together. Remember that when you use `libtool` to link a program, you need to use @LTLIBINTL@ instead of @LIBINTL@ for that program.

### 13.4.12 ‘`gettext.h`’ in ‘`lib/`’

Internationalization of packages, as provided by GNU `gettext`, is optional. It can be turned off in two situations:

- When the installer has specified ‘`./configure --disable-nls`’. This can be useful when small binaries are more important than features, for example when building utilities for boot diskettes. It can also be useful in order to get some specific C compiler warnings about code quality with some older versions of GCC (older than 3.0).
- When the libintl.h header (with its associated libintl library, if any) is not already installed on the system, it is preferable that the package builds without internationalization support, rather than to give a compilation error.

A C preprocessor macro can be used to detect these two cases. Usually, when `libintl.h` was found and not explicitly disabled, the `ENABLE_NLS` macro will be defined to 1 in the autoconf generated configuration file (usually called ‘`config.h`’). In the two negative situations, however, this macro will not be defined, thus it will evaluate to 0 in C preprocessor expressions.

‘`gettext.h`’ is a convenience header file for conditional use of ‘`<libintl.h>`’, depending on the `ENABLE_NLS` macro. If `ENABLE_NLS` is set, it includes ‘`<libintl.h>`’; otherwise it defines no-op substitutes for the libintl.h functions. We recommend the use of `"gettext.h"` over direct use of ‘`<libintl.h>`’, so that portability to older systems is guaranteed and installers can turn off internationalization if they want to. In the C code, you will then write

    #include "gettext.h"

instead of

    #include <libintl.h>

The location of `gettext.h` is usually in a directory containing auxiliary include files. In many GNU packages, there is a directory ‘`lib/`’ containing helper functions; ‘`gettext.h`’ fits there. In other packages, it can go into the ‘`src`’ directory.

Do not install the `gettext.h` file in public locations. Every package that needs it should contain a copy of it on its own.

## 13.5 Autoconf macros for use in ‘`configure.ac`’

GNU `gettext` installs macros for use in a package's ‘`configure.ac`’ or ‘`configure.in`’. See (autoconf)Top section `Introduction' in The Autoconf Manual. The primary macro is, of course, `AM_GNU_GETTEXT`.

### 13.5.1 AM_GNU_GETTEXT in ‘`gettext.m4`’

The `AM_GNU_GETTEXT` macro tests for the presence of the GNU gettext function family in either the C library or a separate `libintl` library (shared or static libraries are both supported). It also invokes `AM_PO_SUBDIRS`, thus preparing the ‘`po/`’ directories of the package for building.

`AM_GNU_GETTEXT` accepts up to two optional arguments. The general syntax is

    AM_GNU_GETTEXT([intlsymbol], [needsymbol])

intlsymbol should always be ‘`external`’.

If needsymbol is specified and is ‘`need-ngettext`’, then GNU gettext implementations (in libc or libintl) without the `ngettext()` function will be ignored. If needsymbol is specified and is ‘`need-formatstring-macros`’, then GNU gettext implementations that don't support the ISO C 99 ‘`<inttypes.h>`’ formatstring macros will be ignored. Only one needsymbol can be specified. These requirements can also be specified by using the macro `AM_GNU_GETTEXT_NEED` elsewhere. To specify more than one requirement, just specify the strongest one among them, or invoke the `AM_GNU_GETTEXT_NEED` macro several times. The hierarchy among the various alternatives is as follows: ‘`need-formatstring-macros`’ implies ‘`need-ngettext`’.

The `AM_GNU_GETTEXT` macro determines whether GNU gettext is available and should be used. If so, it sets the `USE_NLS` variable to ‘`yes`’; it defines `ENABLE_NLS` to 1 in the autoconf generated configuration file (usually called ‘`config.h`’); it sets the variables `LIBINTL` and `LTLIBINTL` to the linker options for use in a Makefile (`LIBINTL` for use without libtool, `LTLIBINTL` for use with libtool); it adds an ‘`-I`’ option to `CPPFLAGS` if necessary. In the negative case, it sets `USE_NLS` to ‘`no`’; it sets `LIBINTL` and `LTLIBINTL` to empty and doesn't change `CPPFLAGS`.

The complexities that `AM_GNU_GETTEXT` deals with are the following:

- Some operating systems have `gettext` in the C library, for example glibc. Some have it in a separate library `libintl`. GNU `libintl` might have been installed as part of the GNU `gettext` package.
- GNU `libintl`, if installed, is not necessarily already in the search path (`CPPFLAGS` for the include file search path, `LDFLAGS` for the library search path).
- Except for glibc and the Solaris 11 libc, the operating system's native `gettext` cannot exploit the GNU mo files, doesn't have the necessary locale dependency features, and cannot convert messages from the catalog's text encoding to the user's locale encoding.
- GNU `libintl`, if installed, is not necessarily already in the run time library search path. To avoid the need for setting an environment variable like `LD_LIBRARY_PATH`, the macro adds the appropriate run time search path options to the `LIBINTL` and `LTLIBINTL` variables. This works on most systems, but not on some operating systems with limited shared library support, like SCO.
- GNU `libintl` relies on POSIX/XSI `iconv`. The macro checks for linker options needed to use iconv and appends them to the `LIBINTL` and `LTLIBINTL` variables.

Additionally, the `AM_GNU_GETTEXT` macro sets two variables, for convenience. Both are derived from the `--localedir` configure option. They are correct even on native Windows, where directories frequently contain backslashes.

`localedir_c`

  This is the value of `localedir`, in C syntax. This variable is meant to be substituted into C or C++ code through `AC_CONFIG_FILES`.

`localedir_c_make`

  This is the value of `localedir`, in C syntax, escaped for use in a `Makefile`. This variable is meant to be used in Makefiles, for example for defining a C macro named `LOCALEDIR`:

      AM_CPPFLAGS = ... -DLOCALEDIR=$(localedir_c_make) ...

### 13.5.2 AM_GNU_GETTEXT_VERSION in ‘`gettext.m4`’

The `AM_GNU_GETTEXT_VERSION` macro declares the version number of the GNU gettext infrastructure that is used by the package.

The use of this macro is optional; only the `autopoint` program makes use of it (see section Integrating with Version Control Systems).

### 13.5.3 AM_GNU_GETTEXT_NEED in ‘`gettext.m4`’

The `AM_GNU_GETTEXT_NEED` macro declares a constraint regarding the GNU gettext implementation. The syntax is

    AM_GNU_GETTEXT_NEED([needsymbol])

If needsymbol is ‘`need-ngettext`’, then GNU gettext implementations (in libc or libintl) without the `ngettext()` function will be ignored. If needsymbol is ‘`need-formatstring-macros`’, then GNU gettext implementations that don't support the ISO C 99 ‘`<inttypes.h>`’ formatstring macros will be ignored.

The optional second argument of `AM_GNU_GETTEXT` is also taken into account.

The `AM_GNU_GETTEXT_NEED` invocations can occur before or after the `AM_GNU_GETTEXT` invocation; the order doesn't matter.

### 13.5.4 AM_PO_SUBDIRS in ‘`po.m4`’

The `AM_PO_SUBDIRS` macro prepares the ‘`po/`’ directories of the package for building. This macro should be used in internationalized programs written in other programming languages than C, C++, Objective C, for example `sh`, `Python`, `Lisp`. See Other Programming Languages for a list of programming languages that support localization through PO files.

The `AM_PO_SUBDIRS` macro determines whether internationalization should be used. If so, it sets the `USE_NLS` variable to ‘`yes`’, otherwise to ‘`no`’. It also determines the right values for Makefile variables in each ‘`po/`’ directory.

### 13.5.5 AM_XGETTEXT_OPTION in ‘`po.m4`’

The `AM_XGETTEXT_OPTION` macro registers a command-line option to be used in the invocations of `xgettext` in the ‘`po/`’ directories of the package.

For example, if you have a source file that defines a function ‘`error_at_line`’ whose fifth argument is a format string, you can use

    AM_XGETTEXT_OPTION([--flag=error_at_line:5:c-format])

to instruct `xgettext` to mark all translatable strings in ‘`gettext`’ invocations that occur as fifth argument to this function as ‘`c-format`’.

See Invoking the `xgettext` Program for the list of options that `xgettext` accepts.

The use of this macro is an alternative to the use of the ‘`XGETTEXT_OPTIONS`’ variable in ‘`po/Makevars`’.

### 13.5.6 AM_ICONV in ‘`iconv.m4`’

The `AM_ICONV` macro tests for the presence of the POSIX/XSI `iconv` function family in either the C library or a separate `libiconv` library. If found, it sets the `am_cv_func_iconv` variable to ‘`yes`’; it defines `HAVE_ICONV` to 1 in the autoconf generated configuration file (usually called ‘`config.h`’); it defines `ICONV_CONST` to ‘`const`’ or to empty, depending on whether the second argument of `iconv()` is of type ‘`const char **`’ or ‘`char **`’; it sets the variables `LIBICONV` and `LTLIBICONV` to the linker options for use in a Makefile (`LIBICONV` for use without libtool, `LTLIBICONV` for use with libtool); it adds an ‘`-I`’ option to `CPPFLAGS` if necessary. If not found, it sets `LIBICONV` and `LTLIBICONV` to empty and doesn't change `CPPFLAGS`.

The complexities that `AM_ICONV` deals with are the following:

- Some operating systems have `iconv` in the C library, for example glibc. Some have it in a separate library `libiconv`, for example OSF/1 or FreeBSD. Regardless of the operating system, GNU `libiconv` might have been installed. In that case, it should be used instead of the operating system's native `iconv`.
- GNU `libiconv`, if installed, is not necessarily already in the search path (`CPPFLAGS` for the include file search path, `LDFLAGS` for the library search path).
- GNU `libiconv` is binary incompatible with some operating system's native `iconv`, for example on FreeBSD. Use of an ‘`iconv.h`’ and ‘`libiconv.so`’ that don't fit together would produce program crashes.
- GNU `libiconv`, if installed, is not necessarily already in the run time library search path. To avoid the need for setting an environment variable like `LD_LIBRARY_PATH`, the macro adds the appropriate run time search path options to the `LIBICONV` variable. This works on most systems, but not on some operating systems with limited shared library support, like SCO.

‘`iconv.m4`’ is distributed with the GNU gettext package because ‘`gettext.m4`’ relies on it.

## 13.6 Integrating with Version Control Systems

Many projects use version control systems for distributed development and source backup. This section gives some advice how to manage the uses of `gettextize`, `autopoint` and `autoconf` on version controlled files.

### 13.6.1 Avoiding version mismatch in distributed development

In a project development with multiple developers, there should be a single developer who occasionally - when there is desire to upgrade to a new `gettext` version - runs `gettextize` and performs the changes listed in Files You Must Create or Alter, and then commits his changes to the repository.

It is highly recommended that all developers on a project use the same version of GNU `gettext` in the package. In other words, if a developer runs `gettextize`, he should go the whole way, make the necessary remaining changes and commit his changes to the repository. Otherwise the following damages will likely occur:

- Apparent version mismatch between developers. Since some `gettext` specific portions in ‘`configure.ac`’, ‘`configure.in`’ and `Makefile.am`, `Makefile.in` files depend on the `gettext` version, the use of infrastructure files belonging to different `gettext` versions can easily lead to build errors.
- Hidden version mismatch. Such version mismatch can also lead to malfunctioning of the package, that may be undiscovered by the developers. The worst case of hidden version mismatch is that internationalization of the package doesn't work at all.
- Release risks. All developers implicitly perform constant testing on a package. This is important in the days and weeks before a release. If the guy who makes the release tar files uses a different version of GNU `gettext` than the other developers, the distribution will be less well tested than if all had been using the same `gettext` version. For example, it is possible that a platform specific bug goes undiscovered due to this constellation.

### 13.6.2 Files to put under version control

There are basically three ways to deal with generated files in the context of a version controlled repository, such as ‘`configure`’ generated from ‘`configure.ac`’, `parser.c` generated from `parser.y`, or `po/Makefile.in.in` autoinstalled by `gettextize` or `autopoint`.

1. All generated files are always committed into the repository.
2. All generated files are committed into the repository occasionally, for example each time a release is made.
3. Generated files are never committed into the repository.

Each of these three approaches has different advantages and drawbacks.

1. The advantage is that anyone can check out the source at any moment and gets a working build. The drawbacks are: 1a. It requires some frequent "push" actions by the maintainers. 1b. The repository grows in size quite fast.
2. The advantage is that anyone can check out the source, and the usual "./configure; make" will work. The drawbacks are: 2a. The one who checks out the repository needs tools like GNU `automake`, GNU `autoconf`, GNU `m4` installed in his PATH; sometimes he even needs particular versions of them. 2b. When a release is made and a commit is made on the generated files, the other developers get conflicts on the generated files when merging the local work back to the repository. Although these conflicts are easy to resolve, they are annoying.
3. The advantage is less work for the maintainers. The drawback is that anyone who checks out the source not only needs tools like GNU `automake`, GNU `autoconf`, GNU `m4` installed in his PATH, but also that he needs to perform a package specific pre-build step before being able to "./configure; make".

For the first and second approach, all files modified or brought in by the occasional `gettextize` invocation and update should be committed into the repository.

For the third approach, the maintainer can omit from the repository all the files that `gettextize` mentions as "copy". Instead, he adds to the ‘`configure.ac`’ or ‘`configure.in`’ a line of the form

    AM_GNU_GETTEXT_VERSION(0.22.2)

and adds to the package's pre-build script an invocation of ‘`autopoint`’. For everyone who checks out the source, this `autopoint` invocation will copy into the right place the `gettext` infrastructure files that have been omitted from the repository.

The version number used as argument to `AM_GNU_GETTEXT_VERSION` is the version of the `gettext` infrastructure that the package wants to use. It is also the minimum version number of the ‘`autopoint`’ program. So, if you write `AM_GNU_GETTEXT_VERSION(0.11.5)` then the developers can have any version >= 0.11.5 installed; the package will work with the 0.11.5 infrastructure in all developers' builds. When the maintainer then runs gettextize from, say, version 0.12.1 on the package, the occurrence of `AM_GNU_GETTEXT_VERSION(0.11.5)` will be changed into `AM_GNU_GETTEXT_VERSION(0.12.1)`, and all other developers that use the CVS will henceforth need to have GNU `gettext` 0.12.1 or newer installed.

### 13.6.3 Put PO Files under Version Control

Since translations are valuable assets as well as the source code, it would make sense to put them under version control. The GNU gettext infrastructure supports two ways to deal with translations in the context of a version controlled repository.

1. Both POT file and PO files are committed into the repository.
2. Only PO files are committed into the repository.

If a POT file is absent when building, it will be generated by scanning the source files with `xgettext`, and then the PO files are regenerated as a dependency. On the other hand, some maintainers want to keep the POT file unchanged during the development phase. So, even if a POT file is present and older than the source code, it won't be updated automatically. You can manually update it with `make $(DOMAIN).pot-update`, and commit it at certain point.

Special advices for particular version control systems:

- Recent version control systems, Git for instance, ignore file's timestamp. In that case, PO files can be accidentally updated even if a POT file is not updated. To prevent this, you can set ‘`PO_DEPENDS_ON_POT`’ variable to `no` in the ‘`Makevars`’ file and do `make update-po` manually.
- Location comments such as `#: lib/error.c:116` are sometimes annoying, since these comments are volatile and may introduce unwanted change to the working copy when building. To mitigate this, you can decide to omit those comments from the PO files in the repository.

  This is possible with the `--no-location` option of the `msgmerge` command (6). The drawback is that, if the location information is needed, translators have to recover the location comments by running `msgmerge` again.

### 13.6.4 Invoking the `autopoint` Program

    autopoint [option]...

The `autopoint` program copies standard gettext infrastructure files into a source package. It extracts from a macro call of the form `AM_GNU_GETTEXT_VERSION(version)`, found in the package's ‘`configure.in`’ or ‘`configure.ac`’ file, the gettext version used by the package, and copies the infrastructure files belonging to this version into the package.

To extract the latest available infrastructure which satisfies a version requirement, then you can use the form `AM_GNU_GETTEXT_REQUIRE_VERSION(version)` instead. For example, if gettext 0.22.2 is installed on your system and `0.19.1` is requested, then the infrastructure files of version 0.22.2 will be copied into a source package.

#### 13.6.4.1 Options

‘`-f`’
‘`--force`’

  Force overwriting of files that already exist.

‘`-n`’
‘`--dry-run`’

  Print modifications but don't perform them. All file copying actions that `autopoint` would normally execute are inhibited and instead only listed on standard output.

#### 13.6.4.2 Informative output

‘`--help`’

  Display this help and exit.

‘`--version`’

  Output version information and exit.

`autopoint` supports the GNU `gettext` versions from 0.10.35 to the current one, 0.22.2. In order to apply `autopoint` to a package using a `gettext` version newer than 0.22.2, you need to install this same version of GNU `gettext` at least.

In packages using GNU `automake`, an invocation of `autopoint` should be followed by invocations of `aclocal` and then `autoconf` and `autoheader`. The reason is that `autopoint` installs some autoconf macro files, which are used by `aclocal` to create ‘`aclocal.m4`’, and the latter is used by `autoconf` to create the package's ‘`configure`’ script and by `autoheader` to create the package's ‘`config.h.in`’ include file template.

The name ‘`autopoint`’ is an abbreviation of ‘`auto-po-intl-m4`’; in earlier versions, the tool copied or updated mostly files in the ‘`po`’, ‘`intl`’, ‘`m4`’ directories.

## 13.7 Creating a Distribution Tarball

In projects that use GNU `automake`, the usual commands for creating a distribution tarball, ‘`make dist`’ or ‘`make distcheck`’, automatically update the PO files as needed.

If GNU `automake` is not used, the maintainer needs to perform this update before making a release:

    $ ./configure
    $ (cd po; make update-po)
    $ make distclean

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