In response to recent messages asked for a "how-to" on script
localization, hereis a quick write up on how to localize
"messages" in ksh93 scripts.
An example is the
best way to demonstate the process. Assume we want to localizethe
following very simple shell script called "demo" which is located in
thesubdirectory "/work/msg":
#!/bin/ksh
name="David"
print "Simple demonstration of ksh93 message translation"
print "Message locale is: $LC_MESSAGES"
echo "Hello" print "Goodbye" printf
"Welcome %s\n" $name
print "This string is
not translated because it is not in the message catalog"
exit 0
The shell script is to be localized for
French and Italian users so that they seethe strings enclose
in double quotations (message strings) in their native language.
First
we must rewrite the message strings in a format which the shell
understandsto mean "translate this string if possible by
retrieving the appropriate stringfrom a message catalog."
Here
is the modified version of demo. It works just like the original
version.
#!/bin/ksh
name="David"
print "Simple demonstration
of ksh93 message translation" print "Message locale is:
$LC_MESSAGES"
echo $"Hello"
print $"Goodbye" printf $"Welcome %s\n" $name
print $"This string is not translated because it is not in the message
catalog"
exit 0
The
changes should be obvious, i.e. the use of $"...".
A
decision has to be made as to where to place the localized message
catalogs. Tokeep it simple the decision was to place them in a
subdirectory under where theshell script is located. Thus
the following directory structure was set up:
/work/msg/demo /work/msg/demo/locale
/work/msg/demo/locale/C /work/msg/demo/locale/fr
/work/msg/demo/locale/it
As an aside, AST-BASE supports the following locations
for message catalogsby default:
${ROOT}/share/lib/locale/%l/%C/%N ${ROOT}/share/locale/%l/%C/%N
${ROOT}/lib/locale/%l/%C/%N
where
${ROOT} is the directory containing the shell script and %l,%C and %N
havethe same meaning as when used with NLSPATH. I choose not
to use any of the defaultlocations for this example in order
to demonstrate the use of NLSPATH.
Note the
../locale/C subdirectory. It is mandatory to have a message catalog in
thisdirectory - otherwise message localization does not work.
The message strings inthis message catalog must be the same
as the strings in your script. This messagecatalog is used to
find the appropriate message string to retrieve from otherlocale
message catalogs.
Code in libast
(../libast/port/mg.c) compares the message string from the shellscript
to all the message strings in this message catalog. If there is a
match,the set and member numbers are used to quickly retrieve
the corresponding messagestring from the appropriate locale
message catalog if one exists.
Here is the
C locale message file (demo.msg):
$quote " $set
3 This is the C locale message set 1 "Hello" 2
"Goodbye" 3 "Welcome %s\\n"
I
assume you are familar with message files and catalogs in general so I
am not going toexplain the syntax or layout of the above
message file. Note, however, the use of 3 for the set
number. This is mandatory for ksh93 shell scripts. It is hardcoded into
ksh93.
Use the AST-BASE msggen utility to
generate (compile) the corresponding messagecatalog:
$
msggen locale/C/demo.cat demo.msg
You do not
need the .cat extension. In fact you can call the catalog anythingyou
like but the default is to expect the name of the message catalog to
be exactly the same as the name of the shell script. You can
work around this restriction to a certain extent by using
NLSPATH.
In this case, we set NLSPATH to handle
the .cat extension.
$
NLSPATH=/work/msg/locale/%l/%N.cat; export NLSPATH
where
%l is the language element and %N is the name parameter.
You
can also use msggen to check the compiled message catalog:
$
msggen -l locale/C/demo.cat $quote " $set 3 1
"Hello" 2 "Goodbye" 3 "Welcome %s\\n"
Here
is the French message file (demo.fr.msg):
$quote
" $set 3 This is the French locale message set 1
"Bonjour" 2 "Au Revoir" 3 "Bienvenu %s\\n"
which
is compiled into a French locale message catalog by:
$
msggen locale/fr/demo.cat demo.fr.msg
and here
is the Italian message file (demo.fr.msg):
$quote
" $set 3 This is the Italian locale message set 1
"Ciao" 2 "Addio" 3 "Benvenuto %s\\n"
which
is compiled into an Italian locale message catalog by:
$
msggen locale/it/demo.cat demo.it.msg
Now we
are ready to test the localization of the demo script.
$
LC_MESSAGES=en_US.utf8; export LANG $ ./demo Simple
demonstration of ksh93 message translation Message locale
is: en_US.utf8 Hello Goodbye Welcome
David This string should not be translated because it is
not in the message catalog
$
LC_MESSAGES=fr_FR.utf8; export LANG $ ./demo Simple
demonstration of ksh93 message translation Message locale
is: fr_FR.utf8 Bonjour Au Revoir Bienvenu
David This string should not be translated because it is
not in the message catalog
$
LC_MESSAGES=it_IT.utf8; export LANG $ ./demo Simple
demonstration of ksh93 message translation Message locale
is: it_IT.utf8 Ciao Addio Benvenuto
David This string should not be translated because it is not
in the message catalog
I hope this helps
readers understand how to localize their ksh93 shell scripts. Iwill
write up a better description of the process in my blog in the next few
weeksbut this should be sufficient to get you started.
-
Finnbarr
P.S. Above example tested on version
93t+.
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