Для Иксов есть стандартный модуль Xrm, man -k Xrm
Пример есть простейший под рукой,
/* Xrm example program */
#include <X11/Xlib.h>
#include <X11/Xresource.h>
#include <stdio.h>
#include <string.h>
main(int argc, char **argv)
{
XrmValue xrmv;
char *type, *value;
int status;
XrmDatabase db;
/* initialize Xrm and load our database */
XrmInitialize();
db = XrmGetFileDatabase(".myrc");
/* retrieve our resource and print out the value */
status = XrmGetResource(db, "myResource",
"MyResource", &type, &xrmv);
if (status && (strcmp(type, "String") == 0)) {
value = (char *) xrmv.addr;
printf("resource was %s\n", value);
} else
printf("resource does not exist\n");
/* change the value of the resource */
XrmPutLineResource(&db, "myResource: newValue");
/* write database back to file */
XrmPutFileDatabase(db, ".myrc");
/* free the database from memory */
XrmDestroyDatabase(db);
}
