EXSTR(1) User Commands EXSTR(1)


exstr - extract strings from source files


exstr filename...

exstr -e filename...

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
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of the original C-language source file in which the strings have been
replaced by calls to the message retrieval function gettxt().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

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 msgfile
and msgnum:

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.

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 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)).


Example 1: The following examples show uses of exstr

Assume that the file example.c contains two strings:



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

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

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

produces the following output:

extern char *gettxt();



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();



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

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




files created by mkmsgs(1)


gettxt(1), mkmsgs(1), printf(1), srchtxt(1), gettxt(3C), printf(3C),
setlocale(3C), attributes(7), environ(7)


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)