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.)
xgettext Programxgettext [option] [inputfile] ...
The xgettext program extracts translatable strings from given
input files.
If inputfile is ‘-’, standard input is read.
If the output file is ‘-’ or ‘/dev/stdout’, the output is written to standard output.
C, C++, ObjectiveC, PO, Python,
Lisp, EmacsLisp, librep, Scheme, Smalltalk,
Java, JavaProperties, C#, awk, YCP,
Tcl, Perl, PHP, GCC-source, NXStringTable,
RST, Glade.
--language=C++.
By default the language is guessed depending on the input file name extension.
By default the input files are assumed to be in ASCII.
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"’.
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++.
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.
The default keyword specifications, which are always looked for if not
explicitly disabled, are language dependent. They are:
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.
NSLocalizedString, _,
NSLocalizedStaticString, __.
gettext, ngettext:1,2, eval_gettext,
eval_ngettext:1,2.
gettext, ugettext, dgettext:2,
ngettext:1,2, ungettext:1,2, dngettext:2,3, _.
gettext, ngettext:1,2, gettext-noop.
_.
_.
gettext, ngettext:1,2, gettext-noop.
GettextResource.gettext:2,
GettextResource.ngettext:2,3, gettext, ngettext:1,2,
getString.
GetString, GetPluralString:1,2.
dcgettext, dcngettext:1,2.
::msgcat::mc.
gettext, %gettext, $gettext, dgettext:2,
dcgettext:2, ngettext:1,2, dngettext:2,3,
dcngettext:2,3, gettext_noop.
_, gettext, dgettext:2, dcgettext:2,
ngettext:1,2, dngettext:2,3, dcngettext:2,3.
label, title, text, format,
copyright, comments, preview_text, tooltip.
--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.
--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.
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.
.properties syntax. Note
that this file format doesn't support plural forms and silently drops
obsolete messages.
.strings syntax.
Note that this file format doesn't support plural forms.
.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.
xgettext was first used in the GNU project.
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