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If for some reason it is difficult or unworkable to integrate configuration
file processing with command line option parsing, the libopts
(see section libopts External Procedures) library can still be used to process
configuration files. Below is a Hello, World! greeting program that tries
to load a configuration file ‘hello.conf’ to see if it should use an
alternate greeting or to personalize the salutation.
#include <config.h>
#include <sys/types.h>
#include <stdio.h>
#include <pwd.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <autoopts/options.h>
int main(int argc, char ** argv) {
char const * greeting = "Hello";
char const * greeted = "World";
tOptionValue const * pOV = configFileLoad("hello.conf");
if (pOV != NULL) {
const tOptionValue* pGetV = optionGetValue(pOV, "greeting");
if ( (pGetV != NULL)
&& (pGetV->valType == OPARG_TYPE_STRING))
greeting = strdup(pGetV->v.strVal);
pGetV = optionGetValue(pOV, "personalize");
if (pGetV != NULL) {
struct passwd * pwe = getpwuid(getuid());
if (pwe != NULL)
greeted = strdup(pwe->pw_gecos);
}
optionUnloadNested(pOV); /* deallocate config data */
}
printf("%s, %s!\n", greeting, greeted);
return 0;
}
|
With that text in a file named “hello.c”, this short script:
cc -o hello hello.c `autoopts-config cflags ldflags` ./hello echo 'greeting Buzz off' > hello.conf ./hello echo personalize > hello.conf ./hello |
will produce the following output:
Hello, World! Buzz off, World! Hello, Bruce Korb! |
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This document was generated by Bruce Korb on August 21, 2015 using texi2html 1.82.