Tribblix: manual page: exstr.1

EXSTR(1) User Commands EXSTR(1)

NAME

exstr - extract strings from source files

SYNOPSIS

exstr filename...

exstr -e filename...

exstr -r [-d] filename...

DESCRIPTION

The exstr utility is used to extract strings from C-language source
files and replace them by calls to the message retrieval function
(see gettxt(3C)). This utility will extract all character strings
surrounded by double quotes, not just strings used as arguments to
the printf command or the printf routine. In the first form, exstr
finds all strings in the source files and writes them on the standard
output. Each string is preceded by the source file name and a colon
(:).

The first step is to use exstr -e to extract a list of strings and
save it in a file. Next, examine this list and determine which
strings can be translated and subsequently retrieved by the message
retrieval function. Then, modify this file by deleting lines that
can't be translated and, for lines that can be translated, by adding
the message file names and the message numbers as the fourth
(msgfile) and fifth (msgnum) entries on a line. The message files
named must have been created by mkmsgs(1) and exist in
/usr/lib/locale/locale/LC_MESSAGES . (The directory locale
corresponds to the language in which the text strings are written;
see setlocale(3C)). The message numbers used must correspond to the
sequence numbers of strings in the message files.

Now use this modified file as input to exstr -r to produce a new
version of the original C-language source file in which the strings
have been replaced by calls to the message retrieval function
gettxt(). The msgfile and msgnum fields are used to construct the
first argument to gettxt(). The second argument to gettxt() is
printed if the message retrieval fails at run-time. This argument is
the null string, unless the -d option is used.

This utility cannot replace strings in all instances. For example, a
static initialized character string cannot be replaced by a function
call. A second example is that a string could be in a form of an
escape sequence which could not be translated. In order not to break
existing code, the files created by invoking exstr -e must be
examined and lines containing strings not replaceable by function
calls must be deleted. In some cases the code may require
modifications so that strings can be extracted and replaced by calls
to the message retrieval function.

OPTIONS

The following options are supported:

-e
Extract a list of strings from the named C-language source
files, with positional information. This list is produced on
standard output in the following format:

file:line:position:msgfile:msgnum:string

file

the name of a C-language source file

line

line number in the file

position

character position in the line

msgfile

null

msgnum

null

string

the extracted text string

Normally you would redirect this output into a file. Then you
would edit this file to add the values you want to use for
msgfile and msgnum:

msgfile
the file that contains the text strings that will
replace string. A file with this name must be
created and installed in the appropriate place by
the mkmsgs(1) utility.

msgnum
the sequence number of the string in msgfile.

The next step is to use exstr -r to replace strings in file.

-r
Replace strings in a C-language source file with function
calls to the message retrieval function gettxt().

-d
This option is used together with the -r option. If the
message retrieval fails when gettxt() is invoked at run-time,
then the extracted string is printed. You would use the
capability provided by exstr on an application program that
needs to run in an international environment and have messages
print in more than one language. exstr replaces text strings
with function calls that point at strings in a message data
base. The data base used depends on the run-time value of the
LC_MESSAGES environment variable (see environ(7)).

EXAMPLES

Example 1: The following examples show uses of exstr

Assume that the file example.c contains two strings:

main()

{

printf("This is an example\n");

printf("Hello world!\n");

}

The exstr utility, invoked with the argument example.c extracts
strings from the named file and prints them on the standard output.

example% exstr example.c

produces the following output:

example.c:This is an example\n
example.c:Hello world!\n

The exstr utility, invoked with the -e option and the argument
example.c, and redirecting output to the file example.stringsout

example% exstr -e example.c > example.stringsout

produces the following output in the file example.stringsout

example.c:3:8:::This is an example\n
example.c:4:8:::Hello world!\n

You must edit example.stringsout to add the values you want to use
for the msgfile and msgnum fields before these strings can be
replaced by calls to the retrieval function. If UX is the name of the
message file, and the numbers 1 and 2 represent the sequence number
of the strings in the file, here is what example.stringsout looks
like after you add this information:

example.c:3:8:UX:1:This is an example\n
example.c:4:8:UX:2:Hello world!\n

The exstr utility can now be invoked with the -r option to replace
the strings in the source file by calls to the message retrieval
function gettxt().

example% exstr -r example.c <example.stringsout >intlexample.c

produces the following output:

extern char *gettxt();

main()

{

printf(gettxt("UX:1", ""));

printf(gettxt("UX:2", ""));

}

The following example:

example% exstr -rd example.c <example.stringsout >intlexample.c

uses the extracted strings as a second argument to gettxt():

extern char *gettxt();

main()

{

printf(gettxt("UX:1", "This is an example\n"));

printf(gettxt("UX:2", "Hello world!\n"));

}

FILES

/usr/lib/locale/locale/LC_MESSAGES/*

files created by mkmsgs(1)

DIAGNOSTICS

The error messages produced by exstr are intended to be self-
explanatory. They indicate errors in the command line or format
errors encountered within the input file.

July 5, 1990 EXSTR(1)