GNU gettext utilities: 5. Making the PO Template File

[ << ] | [ >> ] |  |  |  |  |  | [Top] | [Contents] | [Index] | [ ? ]

# 5. 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.

`xgettext` creates a file named ‘`domainname.po`’. You should then rename it to ‘`domainname.pot`’. (Why doesn't `xgettext` create it under the name ‘`domainname.pot`’ right away? The answer is: for historical reasons. When `xgettext` was specified, the distinction between a PO file and PO file template was fuzzy, and the suffix ‘`.pot`’ wasn't in use at that time.)

## 5.1 Invoking the `xgettext` Program

    xgettext [option] [inputfile] …

The `xgettext` program extracts translatable strings from given input files.

### 5.1.1 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.

### 5.1.2 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.

### 5.1.3 Choice of input file language

‘`-L name`’
‘`--language=name`’

  Specifies the language of the input files. The supported languages are `C`, `C++`, `ObjectiveC`, `PO`, `Shell`, `Python`, `Lisp`, `EmacsLisp`, `librep`, `Scheme`, `Guile`, `Smalltalk`, `Java`, `JavaProperties`, `C#`, `awk`, `YCP`, `Tcl`, `Perl`, `PHP`, `Ruby`, `GCC-source`, `NXStringTable`, `RST`, `RSJ`, `Glade`, `Lua`, `JavaScript`, `Vala`, `GSettings`, `Desktop`.

‘`-C`’
‘`--c++`’

  This is a shorthand for `--language=C++`.

By default the language is guessed depending on the input file name extension.

### 5.1.4 Input file interpretation

‘`--from-code=name`’

  Specifies the encoding of the input files. This option is needed only if some untranslated message strings or their corresponding comments contain non-ASCII characters. Note that Tcl and Glade input files are always assumed to be in UTF-8, regardless of this option.

By default the input files are assumed to be in ASCII.

### 5.1.5 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 blocks starting with tag and preceding keyword lines in the output file. Without a tag, the option means to put all comment blocks preceding keyword lines in the output file.

  Note that comment blocks are only extracted if there is no program code between the comment and the string that gets extracted. For example, in the following C source code:

      /* This is the first comment.  */
      gettext ("foo");

      /* This is the second comment: not extracted  */
      gettext (
        "bar");

      gettext (
        /* This is the third comment.  */
        "baz");

      /* This is the fourth comment.  */

      gettext ("I love blank lines in my programs");

  the second comment line will not be extracted, because there is a line with some tokens between the comment line and the line that contains the string. But the fourth comment is extracted, because between it and the line with the string there is merely a blank line.

‘`--check[=CHECK]`’

  Perform a syntax check on msgid and msgid_plural. The supported checks are:

  ‘`ellipsis-unicode`’

    Prefer Unicode ellipsis character over ASCII `...`

  ‘`space-ellipsis`’

    Prohibit whitespace before an ellipsis character

  ‘`quote-unicode`’

    Prefer Unicode quotation marks over ASCII `"'``

  ‘`bullet-unicode`’

    Prefer Unicode bullet character over ASCII `*` or `-`

  The option has an effect on all input files. To enable or disable checks for a certain string, you can mark it with an `xgettext:` special comment in the source file. For example, if you specify the `--check=space-ellipsis` option, but want to suppress the check on a particular string, add the following comment:

      /* xgettext: no-space-ellipsis-check */
      gettext ("We really want a space before ellipsis here ...");

  The `xgettext:` comment can be followed by flags separated with a comma. The possible flags are of the form ‘`[no-]name-check`’, where name is the name of a valid syntax check. If a flag is prefixed by `no-`, the meaning is negated.

  Some tests apply the checks to each sentence within the msgid, rather than the whole string. xgettext detects the end of sentence by performing a pattern match, which usually looks for a period followed by a certain number of spaces. The number is specified with the `--sentence-end` option.

‘`--sentence-end[=TYPE]`’

  The supported values are:

  ‘`single-space`’

    Expect at least one whitespace after a period

  ‘`double-space`’

    Expect at least two whitespaces after a period

### 5.1.6 Language specific options

‘`-a`’
‘`--extract-all`’

  Extract all strings.

  This option has an effect with most languages, namely C, C++, ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Java, C#, awk, Tcl, Perl, PHP, GCC-source, Glade, Lua, JavaScript, Vala, GSettings.

‘`-k[keywordspec]`’
‘`--keyword[=keywordspec]`’

  Specify keywordspec as an additional keyword to be looked for. Without a keywordspec, the option means to not use default keywords.

  If keywordspec is a C identifier 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. Also, if keywordspec is of the form ‘`id:contextargnumc,argnum`’ or ‘`id:argnum,contextargnumc`’, `xgettext` treats strings in the contextargnumth argument as a context specifier. And, as a special-purpose support for GNOME, if keywordspec is of the form ‘`id:argnumg`’, `xgettext` recognizes the argnumth argument as a string with context, using the GNOME `glib` syntax ‘`"msgctxt|msgid"`’.
  Furthermore, if keywordspec is of the form ‘`id:…,totalnumargst`’, `xgettext` recognizes this argument specification only if the number of actual arguments is equal to totalnumargs. This is useful for disambiguating overloaded function calls in C++.
  Finally, if keywordspec is of the form ‘`id:argnum...,"xcomment"`’, `xgettext`, when extracting a message from the specified argument strings, adds an extracted comment xcomment to the message. Note that when used through a normal shell command line, the double-quotes around the xcomment need to be escaped.

  This option has an effect with most languages, namely C, C++, ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Java, C#, awk, Tcl, Perl, PHP, GCC-source, Glade, Lua, JavaScript, Vala, GSettings, Desktop.

  The default keyword specifications, which are always looked for if not explicitly disabled, are language dependent. They are:

  - For C, C++, and GCC-source: `gettext`, `dgettext:2`, `dcgettext:2`, `ngettext:1,2`, `dngettext:2,3`, `dcngettext:2,3`, `gettext_noop`, and `pgettext:1c,2`, `dpgettext:2c,3`, `dcpgettext:2c,3`, `npgettext:1c,2,3`, `dnpgettext:2c,3,4`, `dcnpgettext:2c,3,4`.
  - For Objective C: Like for C, and also `NSLocalizedString`, `_`, `NSLocalizedStaticString`, `__`.
  - For Shell scripts: `gettext`, `ngettext:1,2`, `eval_gettext`, `eval_ngettext:1,2`, `eval_pgettext:1c,2`, `eval_npgettext:1c,2,3`.
  - For Python: `gettext`, `ugettext`, `dgettext:2`, `ngettext:1,2`, `ungettext:1,2`, `dngettext:2,3`, `_`.
  - For Lisp: `gettext`, `ngettext:1,2`, `gettext-noop`.
  - For EmacsLisp: `_`.
  - For librep: `_`.
  - For Scheme and Guile: `gettext`, `ngettext:1,2`, `gettext-noop`.
  - For Java: `GettextResource.gettext:2`, `GettextResource.ngettext:2,3`, `GettextResource.pgettext:2c,3`, `GettextResource.npgettext:2c,3,4`, `gettext`, `ngettext:1,2`, `pgettext:1c,2`, `npgettext:1c,2,3`, `getString`.
  - For C#: `GetString`, `GetPluralString:1,2`, `GetParticularString:1c,2`, `GetParticularPluralString:1c,2,3`.
  - For awk: `dcgettext`, `dcngettext:1,2`.
  - For Tcl: `::msgcat::mc`.
  - For Perl: `gettext`, `%gettext`, `$gettext`, `dgettext:2`, `dcgettext:2`, `ngettext:1,2`, `dngettext:2,3`, `dcngettext:2,3`, `gettext_noop`.
  - For PHP: `_`, `gettext`, `dgettext:2`, `dcgettext:2`, `ngettext:1,2`, `dngettext:2,3`, `dcngettext:2,3`.
  - For Glade 1: `label`, `title`, `text`, `format`, `copyright`, `comments`, `preview_text`, `tooltip`.
  - For Lua: `_`, `gettext.gettext`, `gettext.dgettext:2`, `gettext.dcgettext:2`, `gettext.ngettext:1,2`, `gettext.dngettext:2,3`, `gettext.dcngettext:2,3`.
  - For JavaScript: `_`, `gettext`, `dgettext:2`, `dcgettext:2`, `ngettext:1,2`, `dngettext:2,3`, `pgettext:1c,2`, `dpgettext:2c,3`.
  - For Vala: `_`, `Q_`, `N_`, `NC_`, `dgettext:2`, `dcgettext:2`, `ngettext:1,2`, `dngettext:2,3`, `dpgettext:2c,3`, `dpgettext2:2c,3`.
  - For Desktop: `Name`, `GenericName`, `Comment`, `Keywords`.

  To disable the default keyword specifications, the option ‘`-k`’ or ‘`--keyword`’ or ‘`--keyword=`’, without a keywordspec, can be used.

‘`--flag=word:arg:flag`’

  Specifies additional flags for strings occurring as part of the argth argument of the function word. The possible flags are the possible format string indicators, such as ‘`c-format`’, and their negations, such as ‘`no-c-format`’, possibly prefixed with ‘`pass-`’.
  The meaning of `--flag=function:arg:lang-format` is that in language lang, the specified function expects as argth argument a format string. (For those of you familiar with GCC function attributes, `--flag=function:arg:c-format` is roughly equivalent to the declaration ‘`__attribute__ ((__format__ (__printf__, arg, ...)))`’ attached to function in a C source file.) For example, if you use the ‘`error`’ function from GNU libc, you can specify its behaviour through `--flag=error:3:c-format`. The effect of this specification is that `xgettext` will mark as format strings all `gettext` invocations that occur as argth argument of function. This is useful when such strings contain no format string directives: together with the checks done by ‘`msgfmt -c`’ it will ensure that translators cannot accidentally use format string directives that would lead to a crash at runtime.
  The meaning of `--flag=function:arg:pass-lang-format` is that in language lang, if the function call occurs in a position that must yield a format string, then its argth argument must yield a format string of the same type as well. (If you know GCC function attributes, the `--flag=function:arg:pass-c-format` option is roughly equivalent to the declaration ‘`__attribute__ ((__format_arg__ (arg)))`’ attached to function in a C source file.) For example, if you use the ‘`_`’ shortcut for the `gettext` function, you should use `--flag=_:1:pass-c-format`. The effect of this specification is that `xgettext` will propagate a format string requirement for a `_("string")` call to its first argument, the literal `"string"`, and thus mark it as a format string. This is useful when such strings contain no format string directives: together with the checks done by ‘`msgfmt -c`’ it will ensure that translators cannot accidentally use format string directives that would lead to a crash at runtime.
  This option has an effect with most languages, namely C, C++, ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Scheme, Guile, Java, C#, awk, YCP, Tcl, Perl, PHP, GCC-source, Lua, JavaScript, Vala.

‘`--tag=word:format`’

  Defines the behaviour of tagged template literals with tag word. This option has an effect only with language JavaScript.
  format is a symbolic description of the first step of the JavaScript function named word, namely how this function constructs a format string based on the parts of the template literal. Currently only one value is supported: `javascript-gnome-format`, which describes the construction of a format string with numbered placeholders `{0}`, `{1}`, `{2}`, etc. For example, `javascript-gnome-format` transforms the template literal `word`My name is ${id.name} and I am ${id.age} years old.`` into the format string `"My name is {0} and I am {1} years old."`.

‘`-T`’
‘`--trigraphs`’

  Understand ANSI C trigraphs for input (deprecated, since trigraphs have been removed from ISO C 23).
  This option has an effect only with the languages C, C++, ObjectiveC.

‘`--qt`’

  Recognize Qt format strings.
  This option has an effect only with the language C++.

‘`--kde`’

  Recognize KDE 4 format strings.
  This option has an effect only with the language C++.

‘`--boost`’

  Recognize Boost format strings.
  This option has an effect only with the language C++.

‘`--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 former 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.

### 5.1.7 Options for XML input files

When some of the input files are XML files and they are not of one of the types covered by the system-wide installed *.its files, a *.its file is needed for each such file type, so that `xgettext` can handle them. There are two ways to specify such a file:

- ‘`--its=file`’

    Use the ITS rules defined in file.

- The environment variable `GETTEXTDATADIRS`. Together with the *.its file, you need a corresponding *.loc file (see section Preparing Rules for XML Internationalization). Furthermore you need to store these files in a directory ‘`parent_dir/its/`’ and set the environment variable `GETTEXTDATADIRS` to include `parent_dir`. More generally, the value of `GETTEXTDATADIRS` should be a colon-separated list of directory names.

Note that when the option `--its` is specified, the system-wide installed *.its files are ignored and the environment variable `GETTEXTDATADIRS` has no effect either.

### 5.1.8 Output details

‘`--color`’
‘`--color=when`’

  Specify whether or when to use colors and other text attributes. See The `--color` option for details.

‘`--style=style_file`’

  Specify the CSS style rule file to use for `--color`. See The `--style` option for 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. Note that using this option makes it harder for technically skilled translators to understand each message's context.

‘`-n`’
‘`--add-location=type`’

  Generate ‘`#: filename:line`’ lines (default).

  The optional type can be either ‘`full`’, ‘`file`’, or ‘`never`’. If it is not given or ‘`full`’, it generates the lines with both file name and line number. If it is ‘`file`’, the line number part is omitted. If it is ‘`never`’, it completely suppresses the lines (same as `--no-location`).

‘`--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.

‘`--properties-output`’

  Write out a Java ResourceBundle in Java `.properties` syntax. Note that this file format doesn't support plural forms and silently drops obsolete messages.

‘`--stringtable-output`’

  Write out a NeXTstep/GNUstep localized resource file in `.strings` syntax. Note that this file format doesn't support plural forms.

‘`--itstool`’

  Write out comments recognized by itstool (http://itstool.org). Note that this is only effective with XML files.

‘`-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.

‘`--no-wrap`’

  Do not break long message lines. Message lines whose width exceeds the output page width will not be split into several lines. Only file reference lines which are wider than the output page width will be split.

‘`-s`’
‘`--sort-output`’

  Generate sorted output (deprecated). 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. Note: Using this option may lead to an error in subsequent operations if the output contains non-ASCII characters.

  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.

  Note that using this option will lead to an error if the resulting file would not entirely be in ASCII.

‘`--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.

‘`--package-name=package`’

  Set the package name in the header of the output.

‘`--package-version=version`’

  Set the package version in the header of the output. This option has an effect only if the ‘`--package-name`’ option is also used.

‘`--msgid-bugs-address=email@address`’

  Set the reporting address for msgid bugs. This is the email address or URL to which the translators shall report bugs in the untranslated strings:

  It can be your email address, or a mailing list address where translators can write to without being subscribed, or the URL of a web page through which the translators can contact you.

  The default value is empty, which means that translators will be clueless! Don't forget to specify this option.

‘`-m[string]`’
‘`--msgstr-prefix[=string]`’

  Use string (or "" if not specified) as prefix for msgstr values.

‘`-M[string]`’
‘`--msgstr-suffix[=string]`’

  Use string (or "" if not specified) as suffix for msgstr values.

### 5.1.9 Informative output

‘`-h`’
‘`--help`’

  Display this help and exit.

‘`-V`’
‘`--version`’

  Output version information and exit.

‘`-v`’
‘`--verbose`’

  Increase verbosity level.

### 5.1.10 Example

A sample invocation of `xgettext`, in a project that has a single source file ‘`src/hello.c`’ that uses ‘`_`’ as shorthand for the `gettext` function, could be:

    xgettext -o hello.pot \
             --add-comments=TRANSLATORS: \
             --keyword=_ --flag=_:1:pass-c-format \
             --directory=.. \
             src/hello.c

## 5.2 Combining PO Template Files

When a package contains sources in different programming languages and different, incompatible `xgettext` command line options are required for these different parts of the package, the solution is to create intermediate PO template files for each of the parts and then combine (merge) them together.

For example, assume you have two source files ‘`a.c`’ and ‘`b.py`’, and want to extract their translatable strings in separate steps.

Each of the following command sequences does this. The output is the same.

- This command sequence creates intermediate POT files and then combines them.

      xgettext -o part-c.pot a.c
      xgettext -o part-py.pot b.py
      xgettext -o all.pot part-c.pot part-py.pot

- This command sequence does several `xgettext` invocations, with a single POT file that accumulates the translatable strings.

      xgettext -o all.pot a.c
      xgettext -o all.pot --join-existing b.py

- Likewise here, but a ‘`--default-domain`’ option is used to denote the output file rather than a ‘`-o`’ option.

      xgettext --default-domain=all a.c
      xgettext --default-domain=all --join-existing b.py
      mv all.po all.pot

One might be tempted to think that ‘`msgcat`’ can do the same thing, through a command sequence such as:

    xgettext -o part-c.pot a.c
    xgettext -o part-py.pot b.py
    msgcat -o all.pot part-c.pot part-py.pot

But no, this does not work reliably, because sometimes `part-c.pot` and `part-py.pot` will contain different `POT-Creation-Date` values, and `msgcat` then produces an `all.pot` file that has conflict markers in the header entry. This is because `msgcat` generally is meant to produce PO files that are to be reviewed and edited by a translator; this is not desired here.

[ << ] | [ >> ] |  |  |  |  |  | [Top] | [Contents] | [Index] | [ ? ]

This document was generated by Bruno Haible on June, 4 2025 using texi2html 1.78a.