This is gettext.info, produced by makeinfo version 4.0 from gettext.texi. INFO-DIR-SECTION GNU Gettext Utilities START-INFO-DIR-ENTRY * Gettext: (gettext). GNU gettext utilities. * gettextize: (gettext)gettextize Invocation. Prepare a package for gettext. * msgfmt: (gettext)msgfmt Invocation. Make MO files out of PO files. * msgmerge: (gettext)msgmerge Invocation. Update two PO files into one. * xgettext: (gettext)xgettext Invocation. Extract strings into a PO file. END-INFO-DIR-ENTRY This file provides documentation for GNU `gettext' utilities. It also serves as a reference for the free Translation Project. Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation.  File: gettext.info, Node: Main PO Commands, Next: Entry Positioning, Prev: PO Files, Up: Basics Main PO mode Commands ===================== After setting up Emacs with something similar to the lines in *Note Installation::, PO mode is activated for a window when Emacs finds a PO file in that window. This puts the window read-only and establishes a po-mode-map, which is a genuine Emacs mode, in a way that is not derived from text mode in any way. Functions found on `po-mode-hook', if any, will be executed. When PO mode is active in a window, the letters `PO' appear in the mode line for that window. The mode line also displays how many entries of each kind are held in the PO file. For example, the string `132t+3f+10u+2o' would tell the translator that the PO mode contains 132 translated entries (*note Translated Entries::, 3 fuzzy entries (*note Fuzzy Entries::), 10 untranslated entries (*note Untranslated Entries::) and 2 obsolete entries (*note Obsolete Entries::). Zero-coefficients items are not shown. So, in this example, if the fuzzy entries were unfuzzied, the untranslated entries were translated and the obsolete entries were deleted, the mode line would merely display `145t' for the counters. The main PO commands are those which do not fit into the other categories of subsequent sections. These allow for quitting PO mode or for managing windows in special ways. `_' Undo last modification to the PO file (`po-undo'). `Q' Quit processing and save the PO file (`po-quit'). `q' Quit processing, possibly after confirmation (`po-confirm-and-quit'). `0' Temporary leave the PO file window (`po-other-window'). `?' `h' Show help about PO mode (`po-help'). `=' Give some PO file statistics (`po-statistics'). `V' Batch validate the format of the whole PO file (`po-validate'). The command `_' (`po-undo') interfaces to the Emacs _undo_ facility. *Note Undoing Changes: (emacs)Undo. Each time `U' is typed, modifications which the translator did to the PO file are undone a little more. For the purpose of undoing, each PO mode command is atomic. This is especially true for the `' command: the whole edition made by using a single use of this command is undone at once, even if the edition itself implied several actions. However, while in the editing window, one can undo the edition work quite parsimoniously. The commands `Q' (`po-quit') and `q' (`po-confirm-and-quit') are used when the translator is done with the PO file. The former is a bit less verbose than the latter. If the file has been modified, it is saved to disk first. In both cases, and prior to all this, the commands check if any untranslated messages remain in the PO file and, if so, the translator is asked if she really wants to leave off working with this PO file. This is the preferred way of getting rid of an Emacs PO file buffer. Merely killing it through the usual command `C-x k' (`kill-buffer') is not the tidiest way to proceed. The command `0' (`po-other-window') is another, softer way, to leave PO mode, temporarily. It just moves the cursor to some other Emacs window, and pops one if necessary. For example, if the translator just got PO mode to show some source context in some other, she might discover some apparent bug in the program source that needs correction. This command allows the translator to change sex, become a programmer, and have the cursor right into the window containing the program she (or rather _he_) wants to modify. By later getting the cursor back in the PO file window, or by asking Emacs to edit this file once again, PO mode is then recovered. The command `h' (`po-help') displays a summary of all available PO mode commands. The translator should then type any character to resume normal PO mode operations. The command `?' has the same effect as `h'. The command `=' (`po-statistics') computes the total number of entries in the PO file, the ordinal of the current entry (counted from 1), the number of untranslated entries, the number of obsolete entries, and displays all these numbers. The command `V' (`po-validate') launches `msgfmt' in checking and verbose mode over the current PO file. This command first offers to save the current PO file on disk. The `msgfmt' tool, from GNU `gettext', has the purpose of creating a MO file out of a PO file, and PO mode uses the features of this program for checking the overall format of a PO file, as well as all individual entries. The program `msgfmt' runs asynchronously with Emacs, so the translator regains control immediately while her PO file is being studied. Error output is collected in the Emacs `*compilation*' buffer, displayed in another window. The regular Emacs command `C-x`' (`next-error'), as well as other usual compile commands, allow the translator to reposition quickly to the offending parts of the PO file. Once the cursor is on the line in error, the translator may decide on any PO mode action which would help correcting the error.  File: gettext.info, Node: Entry Positioning, Next: Normalizing, Prev: Main PO Commands, Up: Basics Entry Positioning ================= The cursor in a PO file window is almost always part of an entry. The only exceptions are the special case when the cursor is after the last entry in the file, or when the PO file is empty. The entry where the cursor is found to be is said to be the current entry. Many PO mode commands operate on the current entry, so moving the cursor does more than allowing the translator to browse the PO file, this also selects on which entry commands operate. Some PO mode commands alter the position of the cursor in a specialized way. A few of those special purpose positioning are described here, the others are described in following sections (for a complete list try `C-h m'): `.' Redisplay the current entry (`po-current-entry'). `n' Select the entry after the current one (`po-next-entry'). `p' Select the entry before the current one (`po-previous-entry'). `<' Select the first entry in the PO file (`po-first-entry'). `>' Select the last entry in the PO file (`po-last-entry'). `m' Record the location of the current entry for later use (`po-push-location'). `r' Return to a previously saved entry location (`po-pop-location'). `x' Exchange the current entry location with the previously saved one (`po-exchange-location'). Any Emacs command able to reposition the cursor may be used to select the current entry in PO mode, including commands which move by characters, lines, paragraphs, screens or pages, and search commands. However, there is a kind of standard way to display the current entry in PO mode, which usual Emacs commands moving the cursor do not especially try to enforce. The command `.' (`po-current-entry') has the sole purpose of redisplaying the current entry properly, after the current entry has been changed by means external to PO mode, or the Emacs screen otherwise altered. It is yet to be decided if PO mode helps the translator, or otherwise irritates her, by forcing a rigid window disposition while she is doing her work. We originally had quite precise ideas about how windows should behave, but on the other hand, anyone used to Emacs is often happy to keep full control. Maybe a fixed window disposition might be offered as a PO mode option that the translator might activate or deactivate at will, so it could be offered on an experimental basis. If nobody feels a real need for using it, or a compulsion for writing it, we should drop this whole idea. The incentive for doing it should come from translators rather than programmers, as opinions from an experienced translator are surely more worth to me than opinions from programmers _thinking_ about how _others_ should do translation. The commands `n' (`po-next-entry') and `p' (`po-previous-entry') move the cursor the entry following, or preceding, the current one. If `n' is given while the cursor is on the last entry of the PO file, or if `p' is given while the cursor is on the first entry, no move is done. The commands `<' (`po-first-entry') and `>' (`po-last-entry') move the cursor to the first entry, or last entry, of the PO file. When the cursor is located past the last entry in a PO file, most PO mode commands will return an error saying `After last entry'. Moreover, the commands `<' and `>' have the special property of being able to work even when the cursor is not into some PO file entry, and one may use them for nicely correcting this situation. But even these commands will fail on a truly empty PO file. There are development plans for the PO mode for it to interactively fill an empty PO file from sources. *Note Marking::. The translator may decide, before working at the translation of a particular entry, that she needs to browse the remainder of the PO file, maybe for finding the terminology or phraseology used in related entries. She can of course use the standard Emacs idioms for saving the current cursor location in some register, and use that register for getting back, or else, use the location ring. PO mode offers another approach, by which cursor locations may be saved onto a special stack. The command `m' (`po-push-location') merely adds the location of current entry to the stack, pushing the already saved locations under the new one. The command `r' (`po-pop-location') consumes the top stack element and repositions the cursor to the entry associated with that top element. This position is then lost, for the next `r' will move the cursor to the previously saved location, and so on until no locations remain on the stack. If the translator wants the position to be kept on the location stack, maybe for taking a look at the entry associated with the top element, then go elsewhere with the intent of getting back later, she ought to use `m' immediately after `r'. The command `x' (`po-exchange-location') simultaneously repositions the cursor to the entry associated with the top element of the stack of saved locations, and replaces that top element with the location of the current entry before the move. Consequently, repeating the `x' command toggles alternatively between two entries. For achieving this, the translator will position the cursor on the first entry, use `m', then position to the second entry, and merely use `x' for making the switch.  File: gettext.info, Node: Normalizing, Prev: Entry Positioning, Up: Basics Normalizing Strings in Entries ============================== There are many different ways for encoding a particular string into a PO file entry, because there are so many different ways to split and quote multi-line strings, and even, to represent special characters by backslashed escaped sequences. Some features of PO mode rely on the ability for PO mode to scan an already existing PO file for a particular string encoded into the `msgid' field of some entry. Even if PO mode has internally all the built-in machinery for implementing this recognition easily, doing it fast is technically difficult. To facilitate a solution to this efficiency problem, we decided on a canonical representation for strings. A conventional representation of strings in a PO file is currently under discussion, and PO mode experiments with a canonical representation. Having both `xgettext' and PO mode converging towards a uniform way of representing equivalent strings would be useful, as the internal normalization needed by PO mode could be automatically satisfied when using `xgettext' from GNU `gettext'. An explicit PO mode normalization should then be only necessary for PO files imported from elsewhere, or for when the convention itself evolves. So, for achieving normalization of at least the strings of a given PO file needing a canonical representation, the following PO mode command is available: `M-x po-normalize' Tidy the whole PO file by making entries more uniform. The special command `M-x po-normalize', which has no associated keys, revises all entries, ensuring that strings of both original and translated entries use uniform internal quoting in the PO file. It also removes any crumb after the last entry. This command may be useful for PO files freshly imported from elsewhere, or if we ever improve on the canonical quoting format we use. This canonical format is not only meant for getting cleaner PO files, but also for greatly speeding up `msgid' string lookup for some other PO mode commands. `M-x po-normalize' presently makes three passes over the entries. The first implements heuristics for converting PO files for GNU `gettext' 0.6 and earlier, in which `msgid' and `msgstr' fields were using K&R style C string syntax for multi-line strings. These heuristics may fail for comments not related to obsolete entries and ending with a backslash; they also depend on subsequent passes for finalizing the proper commenting of continued lines for obsolete entries. This first pass might disappear once all oldish PO files would have been adjusted. The second and third pass normalize all `msgid' and `msgstr' strings respectively. They also clean out those trailing backslashes used by XView's `msgfmt' for continued lines. Having such an explicit normalizing command allows for importing PO files from other sources, but also eases the evolution of the current convention, evolution driven mostly by aesthetic concerns, as of now. It is easy to make suggested adjustments at a later time, as the normalizing command and eventually, other GNU `gettext' tools should greatly automate conformance. A description of the canonical string format is given below, for the particular benefit of those not having Emacs handy, and who would nevertheless want to handcraft their PO files in nice ways. Right now, in PO mode, strings are single line or multi-line. A string goes multi-line if and only if it has _embedded_ newlines, that is, if it matches `[^\n]\n+[^\n]'. So, we would have: msgstr "\n\nHello, world!\n\n\n" but, replacing the space by a newline, this becomes: msgstr "" "\n" "\n" "Hello,\n" "world!\n" "\n" "\n" We are deliberately using a caricatural example, here, to make the point clearer. Usually, multi-lines are not that bad looking. It is probable that we will implement the following suggestion. We might lump together all initial newlines into the empty string, and also all newlines introducing empty lines (that is, for N > 1, the N-1'th last newlines would go together on a separate string), so making the previous example appear: msgstr "\n\n" "Hello,\n" "world!\n" "\n\n" There are a few yet undecided little points about string normalization, to be documented in this manual, once these questions settle.  File: gettext.info, Node: Sources, Next: Template, Prev: Basics, Up: Top Preparing Program Sources ************************* For the programmer, changes to the C source code fall into three categories. First, you have to make the localization functions known to all modules needing message translation. Second, you should properly trigger the operation of GNU `gettext' when the program initializes, usually from the `main' function. Last, you should identify and especially mark all constant strings in your program needing translation. Presuming that your set of programs, or package, has been adjusted so all needed GNU `gettext' files are available, and your `Makefile' files are adjusted (*note Maintainers::), each C module having translated C strings should contain the line: #include The remaining changes to your C sources are discussed in the further sections of this chapter. * Menu: * Triggering:: Triggering `gettext' Operations * Mark Keywords:: How Marks Appear in Sources * Marking:: Marking Translatable Strings * c-format:: Telling something about the following string * Special cases:: Special Cases of Translatable Strings  File: gettext.info, Node: Triggering, Next: Mark Keywords, Prev: Sources, Up: Sources Triggering `gettext' Operations =============================== The initialization of locale data should be done with more or less the same code in every program, as demonstrated below: int main (argc, argv) int argc; char argv; { ... setlocale (LC_ALL, ""); bindtextdomain (PACKAGE, LOCALEDIR); textdomain (PACKAGE); ... } PACKAGE and LOCALEDIR should be provided either by `config.h' or by the Makefile. For now consult the `gettext' sources for more information. The use of `LC_ALL' might not be appropriate for you. `LC_ALL' includes all locale categories and especially `LC_CTYPE'. This later category is responsible for determining character classes with the `isalnum' etc. functions from `ctype.h' which could especially for programs, which process some kind of input language, be wrong. For example this would mean that a source code using the c, (c-cedilla character) is runnable in France but not in the U.S. Some systems also have problems with parsing numbers using the `scanf' functions if an other but the `LC_ALL' locale is used. The standards say that additional formats but the one known in the `"C"' locale might be recognized. But some systems seem to reject numbers in the `"C"' locale format. In some situation, it might also be a problem with the notation itself which makes it impossible to recognize whether the number is in the `"C"' locale or the local format. This can happen if thousands separator characters are used. Some locales define this character accordfing to the national conventions to `'.'' which is the same character used in the `"C"' locale to denote the decimal point. So it is sometimes necessary to replace the `LC_ALL' line in the code above by a sequence of `setlocale' lines { ... setlocale (LC_CTYPE, ""); setlocale (LC_MESSAGES, ""); ... } On all POSIX conformant systems the locale categories `LC_CTYPE', `LC_COLLATE', `LC_MONETARY', `LC_NUMERIC', and `LC_TIME' are available. On some modern systems there is also a locale `LC_MESSAGES' which is called on some old, XPG2 compliant systems `LC_RESPONSES'. Note that changing the `LC_CTYPE' also affects the functions declared in the `' standard header. If this is not desirable in your application (for example in a compiler's parser), you can use a set of substitute functions which hardwire the C locale, such as found in the `' and `' files in the gettext source distribution. It is also possible to switch the locale forth and back between the environment dependent locale and the C locale, but this approach is normally avoided because a `setlocale' call is expensive, because it is tedious to determine the places where a locale switch is needed in a large program's source, and because switching a locale is not multithread-safe.  File: gettext.info, Node: Mark Keywords, Next: Marking, Prev: Triggering, Up: Sources How Marks Appear in Sources =========================== All strings requiring translation should be marked in the C sources. Marking is done in such a way that each translatable string appears to be the sole argument of some function or preprocessor macro. There are only a few such possible functions or macros meant for translation, and their names are said to be marking keywords. The marking is attached to strings themselves, rather than to what we do with them. This approach has more uses. A blatant example is an error message produced by formatting. The format string needs translation, as well as some strings inserted through some `%s' specification in the format, while the result from `sprintf' may have so many different instances that it is impractical to list them all in some `error_string_out()' routine, say. This marking operation has two goals. The first goal of marking is for triggering the retrieval of the translation, at run time. The keyword are possibly resolved into a routine able to dynamically return the proper translation, as far as possible or wanted, for the argument string. Most localizable strings are found in executable positions, that is, attached to variables or given as parameters to functions. But this is not universal usage, and some translatable strings appear in structured initializations. *Note Special cases::. The second goal of the marking operation is to help `xgettext' at properly extracting all translatable strings when it scans a set of program sources and produces PO file templates. The canonical keyword for marking translatable strings is `gettext', it gave its name to the whole GNU `gettext' package. For packages making only light use of the `gettext' keyword, macro or function, it is easily used _as is_. However, for packages using the `gettext' interface more heavily, it is usually more convenient to give the main keyword a shorter, less obtrusive name. Indeed, the keyword might appear on a lot of strings all over the package, and programmers usually do not want nor need their program sources to remind them forcefully, all the time, that they are internationalized. Further, a long keyword has the disadvantage of using more horizontal space, forcing more indentation work on sources for those trying to keep them within 79 or 80 columns. Many packages use `_' (a simple underline) as a keyword, and write `_("Translatable string")' instead of `gettext ("Translatable string")'. Further, the coding rule, from GNU standards, wanting that there is a space between the keyword and the opening parenthesis is relaxed, in practice, for this particular usage. So, the textual overhead per translatable string is reduced to only three characters: the underline and the two parentheses. However, even if GNU `gettext' uses this convention internally, it does not offer it officially. The real, genuine keyword is truly `gettext' indeed. It is fairly easy for those wanting to use `_' instead of `gettext' to declare: #include #define _(String) gettext (String) instead of merely using `#include '. Later on, the maintenance is relatively easy. If, as a programmer, you add or modify a string, you will have to ask yourself if the new or altered string requires translation, and include it within `_()' if you think it should be translated. `"%s: %d"' is an example of string _not_ requiring translation!  File: gettext.info, Node: Marking, Next: c-format, Prev: Mark Keywords, Up: Sources Marking Translatable Strings ============================ In PO mode, one set of features is meant more for the programmer than for the translator, and allows him to interactively mark which strings, in a set of program sources, are translatable, and which are not. Even if it is a fairly easy job for a programmer to find and mark such strings by other means, using any editor of his choice, PO mode makes this work more comfortable. Further, this gives translators who feel a little like programmers, or programmers who feel a little like translators, a tool letting them work at marking translatable strings in the program sources, while simultaneously producing a set of translation in some language, for the package being internationalized. The set of program sources, targetted by the PO mode commands describe here, should have an Emacs tags table constructed for your project, prior to using these PO file commands. This is easy to do. In any shell window, change the directory to the root of your project, then execute a command resembling: etags src/*.[hc] lib/*.[hc] presuming here you want to process all `.h' and `.c' files from the `src/' and `lib/' directories. This command will explore all said files and create a `TAGS' file in your root directory, somewhat summarizing the contents using a special file format Emacs can understand. For packages following the GNU coding standards, there is a make goal `tags' or `TAGS' which constructs the tag files in all directories and for all files containing source code. Once your `TAGS' file is ready, the following commands assist the programmer at marking translatable strings in his set of sources. But these commands are necessarily driven from within a PO file window, and it is likely that you do not even have such a PO file yet. This is not a problem at all, as you may safely open a new, empty PO file, mainly for using these commands. This empty PO file will slowly fill in while you mark strings as translatable in your program sources. `,' Search through program sources for a string which looks like a candidate for translation (`po-tags-search'). `M-,' Mark the last string found with `_()' (`po-mark-translatable'). `M-.' Mark the last string found with a keyword taken from a set of possible keywords. This command with a prefix allows some management of these keywords (`po-select-mark-and-mark'). The `,' (`po-tags-search') command searches for the next occurrence of a string which looks like a possible candidate for translation, and displays the program source in another Emacs window, positioned in such a way that the string is near the top of this other window. If the string is too big to fit whole in this window, it is positioned so only its end is shown. In any case, the cursor is left in the PO file window. If the shown string would be better presented differently in different native languages, you may mark it using `M-,' or `M-.'. Otherwise, you might rather ignore it and skip to the next string by merely repeating the `,' command. A string is a good candidate for translation if it contains a sequence of three or more letters. A string containing at most two letters in a row will be considered as a candidate if it has more letters than non-letters. The command disregards strings containing no letters, or isolated letters only. It also disregards strings within comments, or strings already marked with some keyword PO mode knows (see below). If you have never told Emacs about some `TAGS' file to use, the command will request that you specify one from the minibuffer, the first time you use the command. You may later change your `TAGS' file by using the regular Emacs command `M-x visit-tags-table', which will ask you to name the precise `TAGS' file you want to use. *Note Tag Tables: (emacs)Tags. Each time you use the `,' command, the search resumes from where it was left by the previous search, and goes through all program sources, obeying the `TAGS' file, until all sources have been processed. However, by giving a prefix argument to the command (`C-u ,'), you may request that the search be restarted all over again from the first program source; but in this case, strings that you recently marked as translatable will be automatically skipped. Using this `,' command does not prevent using of other regular Emacs tags commands. For example, regular `tags-search' or `tags-query-replace' commands may be used without disrupting the independent `,' search sequence. However, as implemented, the _initial_ `,' command (or the `,' command is used with a prefix) might also reinitialize the regular Emacs tags searching to the first tags file, this reinitialization might be considered spurious. The `M-,' (`po-mark-translatable') command will mark the recently found string with the `_' keyword. The `M-.' (`po-select-mark-and-mark') command will request that you type one keyword from the minibuffer and use that keyword for marking the string. Both commands will automatically create a new PO file untranslated entry for the string being marked, and make it the current entry (making it easy for you to immediately proceed to its translation, if you feel like doing it right away). It is possible that the modifications made to the program source by `M-,' or `M-.' render some source line longer than 80 columns, forcing you to break and re-indent this line differently. You may use the `O' command from PO mode, or any other window changing command from Emacs, to break out into the program source window, and do any needed adjustments. You will have to use some regular Emacs command to return the cursor to the PO file window, if you want command `,' for the next string, say. The `M-.' command has a few built-in speedups, so you do not have to explicitly type all keywords all the time. The first such speedup is that you are presented with a _preferred_ keyword, which you may accept by merely typing `' at the prompt. The second speedup is that you may type any non-ambiguous prefix of the keyword you really mean, and the command will complete it automatically for you. This also means that PO mode has to _know_ all your possible keywords, and that it will not accept mistyped keywords. If you reply `?' to the keyword request, the command gives a list of all known keywords, from which you may choose. When the command is prefixed by an argument (`C-u M-.'), it inhibits updating any program source or PO file buffer, and does some simple keyword management instead. In this case, the command asks for a keyword, written in full, which becomes a new allowed keyword for later `M-.' commands. Moreover, this new keyword automatically becomes the _preferred_ keyword for later commands. By typing an already known keyword in response to `C-u M-.', one merely changes the _preferred_ keyword and does nothing more. All keywords known for `M-.' are recognized by the `,' command when scanning for strings, and strings already marked by any of those known keywords are automatically skipped. If many PO files are opened simultaneously, each one has its own independent set of known keywords. There is no provision in PO mode, currently, for deleting a known keyword, you have to quit the file (maybe using `q') and reopen it afresh. When a PO file is newly brought up in an Emacs window, only `gettext' and `_' are known as keywords, and `gettext' is preferred for the `M-.' command. In fact, this is not useful to prefer `_', as this one is already built in the `M-,' command.  File: gettext.info, Node: c-format, Next: Special cases, Prev: Marking, Up: Sources Special Comments preceding Keywords =================================== In C programs strings are often used within calls of functions from the `printf' family. The special thing about these format strings is that they can contain format specifiers introduced with `%'. Assume we have the code printf (gettext ("String `%s' has %d characters\n"), s, strlen (s)); A possible German translation for the above string might be: "%d Zeichen lang ist die Zeichenkette `%s'" A C programmer, even if he cannot speak German, will recognize that there is something wrong here. The order of the two format specifiers is changed but of course the arguments in the `printf' don't have. This will most probably lead to problems because now the length of the string is regarded as the address. To prevent errors at runtime caused by translations the `msgfmt' tool can check statically whether the arguments in the original and the translation string match in type and number. If this is not the case and the `-c' option has been passed to `msgfmt', `msgfmt' will give an error and refuse to produce a MO file. Thus consequent use of `msgfmt -c' will catch the error, so that it cannot cause cause problems at runtime. If the word order in the above German translation would be correct one would have to write "%2$d Zeichen lang ist die Zeichenkette `%1$s'" The routines in `msgfmt' know about this special notation. Because not all strings in a program must be format strings it is not useful for `msgfmt' to test all the strings in the `.po' file. This might cause problems because the string might contain what looks like a format specifier, but the string is not used in `printf'. Therefore the `xgettext' adds a special tag to those messages it thinks might be a format string. There is no absolute rule for this, only a heuristic. In the `.po' file the entry is marked using the `c-format' flag in the `#,' comment line (*note PO Files::). The careful reader now might say that this again can cause problems. The heuristic might guess it wrong. This is true and therefore `xgettext' knows about special kind of comment which lets the programmer take over the decision. If in the same line or the immediately preceding line of the `gettext' keyword the `xgettext' program find a comment containing the words `xgettext:c-format' it will mark the string in any case with the `c-format' flag. This kind of comment should be used when `xgettext' does not recognize the string as a format string but is really is one and it should be tested. Please note that when the comment is in the same line of the `gettext' keyword, it must be before the string to be translated. This situation happens quite often. The `printf' function is often called with strings which do not contain a format specifier. Of course one would normally use `fputs' but it does happen. In this case `xgettext' does not recognize this as a format string but what happens if the translation introduces a valid format specifier? The `printf' function will try to access one of the parameter but none exists because the original code does not refer to any parameter. `xgettext' of course could make a wrong decision the other way round, i.e. a string marked as a format string actually is not a format string. In this case the `msgfmt' might give too many warnings and would prevent translating the `.po' file. The method to prevent this wrong decision is similar to the one used above, only the comment to use must contain the string `xgettext:no-c-format'. If a string is marked with `c-format' and this is not correct the user can find out who is responsible for the decision. See *Note xgettext Invocation:: to see how the `--debug' option can be used for solving this problem.  File: gettext.info, Node: Special cases, Prev: c-format, Up: Sources Special Cases of Translatable Strings ===================================== The attentive reader might now point out that it is not always possible to mark translatable string with `gettext' or something like this. Consider the following case: { static const char *messages[] = { "some very meaningful message", "and another one" }; const char *string; ... string = index > 1 ? "a default message" : messages[index]; fputs (string); ... } While it is no problem to mark the string `"a default message"' it is not possible to mark the string initializers for `messages'. What is to be done? We have to fulfill two tasks. First we have to mark the strings so that the `xgettext' program (*note xgettext Invocation::) can find them, and second we have to translate the string at runtime before printing them. The first task can be fulfilled by creating a new keyword, which names a no-op. For the second we have to mark all access points to a string from the array. So one solution can look like this: #define gettext_noop(String) String { static const char *messages[] = { gettext_noop ("some very meaningful message"), gettext_noop ("and another one") }; const char *string; ... string = index > 1 ? gettext ("a default message") : gettext (messages[index]); fputs (string); ... } Please convince yourself that the string which is written by `fputs' is translated in any case. How to get `xgettext' know the additional keyword `gettext_noop' is explained in *Note xgettext Invocation::. The above is of course not the only solution. You could also come along with the following one: #define gettext_noop(String) String { static const char *messages[] = { gettext_noop ("some very meaningful message", gettext_noop ("and another one") }; const char *string; ... string = index > 1 ? gettext_noop ("a default message") : messages[index]; fputs (gettext (string)); ... } But this has a drawback. The programmer has to take care that he uses `gettext_noop' for the string `"a default message"'. A use of `gettext' could have in rare cases unpredictable results. One advantage is that you need not make control flow analysis to make sure the output is really translated in any case. But this analysis is generally not very difficult. If it should be in any situation you can use this second method in this situation.  File: gettext.info, Node: Template, Next: Creating, Prev: Sources, Up: Top Making the PO Template File *************************** After preparing the sources, the programmer creates a PO template file. This section explains how to use `xgettext' for this purpose. * Menu: * xgettext Invocation:: Invoking the `xgettext' Program  File: gettext.info, Node: xgettext Invocation, Prev: Template, Up: Template Invoking the `xgettext' Program =============================== xgettext [OPTION] [INPUTFILE] ... The `xgettext' program extracts translatable strings from given input files. Input file location ------------------- `INPUTFILE ...' Input files. `-f FILE' `--files-from=FILE' Read the names of the input files from FILE instead of getting them from the command line. `-D DIRECTORY' `--directory=DIRECTORY' Add DIRECTORY to the list of directories. Source files are searched relative to this list of directories. The resulting `.po' file will be written relative to the current directory, though. If INPUTFILE is `-', standard input is read. Output file location -------------------- `-d NAME' `--default-domain=NAME' Use `NAME.po' for output (instead of `messages.po'). `-o FILE' `--output=FILE' Write output to specified file (instead of `NAME.po' or `messages.po'). `-p DIR' `--output-dir=DIR' Output files will be placed in directory DIR. If the output FILE is `-' or `/dev/stdout', the output is written to standard output. Choice of input file language ----------------------------- `-L NAME' `--language=NAME' Specifies the language of the input files. The supported languages are `C', `C++', `ObjectiveC', `PO', `Java', `YCP'. `-C' `--c++' This is a shorthand for `--language=C++'. By default the language is guessed depending on the input file name extension. Operation mode -------------- `-j' `--join-existing' Join messages with existing file. `-x FILE' `--exclude-file=FILE' Entries from FILE are not extracted. FILE should be a PO or POT file. `-c [TAG]' `--add-comments[=TAG]' Place comment block with TAG (or those preceding keyword lines) in output file. Language=C/C++ specific options ------------------------------- `-a' `--extract-all' Extract all strings. `-k KEYWORDSPEC' `--keyword[=KEYWORDSPEC]' Additional keyword to be looked for (without KEYWORDSPEC means not to use default keywords). If KEYWORDSPEC is a C identifer ID, `xgettext' looks for strings in the first argument of each call to the function or macro ID. If KEYWORDSPEC is of the form `ID:ARGNUM', `xgettext' looks for strings in the ARGNUMth argument of the call. If KEYWORDSPEC is of the form `ID:ARGNUM1,ARGNUM2', `xgettext' looks for strings in the ARGNUM1st argument and in the ARGNUM2nd argument of the call, and treats them as singular/plural variants for a message with plural handling. The default keyword specifications, which are always looked for if not explicitly disabled, are `gettext', `dgettext:2', `dcgettext:2', `ngettext:1,2', `dngettext:2,3', `dcngettext:2,3', and `gettext_noop'. `-T' `--trigraphs' Understand ANSI C trigraphs for input. `--debug' Use the flags `c-format' and `possible-c-format' to show who was responsible for marking a message as a format string. The latter form is used if the `xgettext' program decided, the format form is used if the programmer prescribed it. By default only the `c-format' form is used. The translator should not have to care about these details. This implementation of `xgettext' is able to process a few awkward cases, like strings in preprocessor macros, ANSI concatenation of adjacent strings, and escaped end of lines for continued strings. Output details -------------- `--force-po' Always write an output file even if no message is defined. `-i' `--indent' Write the .po file using indented style. `--no-location' Do not write `#: FILENAME:LINE' lines. `-n' `--add-location' Generate `#: FILENAME:LINE' lines (default). `--strict' Write out a strict Uniforum conforming PO file. Note that this Uniforum format should be avoided because it doesn't support the GNU extensions. `-w NUMBER' `--width=NUMBER' Set the output page width. Long strings in the output files will be split across multiple lines in order to ensure that each line's width (= number of screen columns) is less or equal to the given NUMBER. `-s' `--sort-output' Generate sorted output. Note that using this option makes it much harder for the translator to understand each message's context. `-F' `--sort-by-file' Sort output by file location. `--omit-header' Don't write header with `msgid ""' entry. This is useful for testing purposes because it eliminates a source of variance for generated `.gmo' files. With `--omit-header', two invocations of `xgettext' on the same files with the same options at different times are guaranteed to produce the same results. `--copyright-holder=STRING' Set the copyright holder in the output. STRING should be the copyright holder of the surrounding package. (Note that the msgstr strings, extracted from the package's sources, belong to the copyright holder of the package.) Translators are expected to transfer or disclaim the copyright for their translations, so that package maintainers can distribute them without legal risk. If STRING is empty, the output files are marked as being in the public domain; in this case, the translators are expected to disclaim their copyright, again so that package maintainers can distribute them without legal risk. The default value for STRING is the Free Software Foundation, Inc., simply because `xgettext' was first used in the GNU project. `--foreign-user' Omit FSF copyright in output. This option is equivalent to `--copyright-holder='''. It can be useful for packages outside the GNU project that want their translations to be in the public domain. `-m [STRING]' `--msgstr-prefix[=STRING]' Use STRING (or "" if not specified) as prefix for msgstr entries. `-M [STRING]' `--msgstr-suffix[=STRING]' Use STRING (or "" if not specified) as suffix for msgstr entries. Informative output ------------------ `-h' `--help' Display this help and exit. `-V' `--version' Output version information and exit.  File: gettext.info, Node: Creating, Next: Updating, Prev: Template, Up: Top Creating a New PO File ********************** When starting a new translation, the translator creates a file called `LANG.po', as a copy of the `PACKAGE.pot' template file with modifications in the initial comments (at the beginning of the file) and in the header entry (the first entry, near the beginning of the file). The easiest way to do so is by use of the `msginit' program. For example: $ cd PACKAGE-VERSION $ cd po $ msginit --verbose The alternative way is to do the copy and modifications by hand. To do so, the translator copies `PACKAGE.pot' to `LANG.po'. Then she modifies the initial comments and the header entry of this file. * Menu: * msginit Invocation:: Invoking the `msginit' Program * Header Entry:: Filling in the Header Entry  File: gettext.info, Node: msginit Invocation, Next: Header Entry, Prev: Creating, Up: Creating Invoking the `msginit' Program ============================== msginit [OPTION] The `msginit' program creates a new PO file, initializing the meta information with values from the user's environment. Input file location ------------------- `-i INPUTFILE' `--input=INPUTFILE' Input POT file. If no INPUTFILE is given, the current directory is searched for the POT file. If it is `-', standard input is read. Output file location -------------------- `-o FILE' `--output-file=FILE' Write output to specified PO file. If no output file is given, it depends on the `--locale' option or the user's locale setting. If it is `-', the results are written to standard output. Output details -------------- `-l LL_CC' `--locale=LL_CC' Set target locale. LL should be a language code, and CC should be a country code. The command `locale -a' can be used to output a list of all installed locales. The default is the user's locale setting. `--no-translator' Declares that the PO file will not have a human translator and is instead automatically generated. `-w NUMBER' `--width=NUMBER' Set the output page width. Long strings in the output files will be split across multiple lines in order to ensure that each line's width (= number of screen columns) is less or equal to the given NUMBER. Informative output ------------------ `-h' `--help' Display this help and exit. `-V' `--version' Output version information and exit.