EXSTR(1)EXSTR(1)NAMEexstr - extract strings from source files
exstr-r [-d] filename...
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 com‐
mand 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 func‐
tion. 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 corre‐
spond to the sequence numbers of strings in the message files.
Now use this modified file as input to exstr-r to produce a new ver‐
sion 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been replaced by calls to the message retrieval function gettxt().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.
The following options are supported:
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:
the name of a C-language source file
line number in the file
character position in the line
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 msg‐
file and msgnum:
the file that contains the text strings that will
replace string. A file with this name must be cre‐
ated and installed in the appropriate place by the
the sequence number of the string in msgfile.
The next step is to use exstr-r to replace strings in file.
Replace strings in a C-language source file with function calls
to the message retrieval function gettxt().
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 pro‐
vided 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(5)).
Example 1 The following examples show uses of exstr
Assume that the file example.c contains two strings:
printf("This is an example\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
The exstr utility, invoked with the -e option and the argument exam‐
ple.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
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
example.c:3:8:UX:1:This is an example\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
example% exstr-r example.c <example.stringsout >intlexample.c
produces the following output:
extern char *gettxt();
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();
printf(gettxt("UX:1", "This is an example\n"));
printf(gettxt("UX:2", "Hello world!\n"));
files created by mkmsgs(1)SEE ALSOgettxt(1), mkmsgs(1), printf(1), srchtxt(1), gettxt(3C), printf(3C),
setlocale(3C), attributes(5), environ(5)DIAGNOSTICS
The error messages produced by exstr are intended to be self-explana‐
tory. They indicate errors in the command line or format errors
encountered within the input file.
Jul 5, 1990 EXSTR(1)