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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, 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:

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, Java, C#, awk, YCP, Tcl, Perl, PHP, GCC-source, Lua, JavaScript, Vala.

-T
--trigraphs

Understand ANSI C trigraphs for input.
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 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.

--its=file

Use ITS rules defined in file. Note that this is only effective with XML files.

--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.

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.

5.1.8 Informative output

-h
--help

Display this help and exit.

-V
--version

Output version information and exit.

-v
--verbose

Increase verbosity level.

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