/** 
 * Read in from the command line
 * and print "hello world" whenever we see a "blah"
 * otherwise, echo what the user typed
 * 
 * flex -o replace.yy.c replace.yy
 * gcc -o replace replace.yy.c -ll
 */

%%
blah    printf("hello world");
%%

int main(int argc, char *argv[]) {
    yylex();
}