$ls first-example first-example.c new-sum.c sum sum.c $cat new-sum.c #define _XOPEN_SOURCE 500 #include <stdio.h> #include <stdlib.h> #include <unistd.h> void printhelp(char progname[]); int main(int argc, char *argv[]) { int i, opt, sum; /* Simple sanity check */ if (argc == 1) { printhelp(argv[0]); return 1; } /* Parse command-line options */ while ((opt = getopt(argc, argv, “smh”))…

$lsfirst-example first-example.c new-sum.c sum.c$gcc sum.c -o sum$cat sum.c #include <stdio.h>#include <stdlib.h>void printhelp(char progname[]); int main(int argc, char *argv[]){int i;int sum = 0; /* Simple sanity check */if (argc == 1){printhelp(argv[0]);return 1;} for (i=1; i<argc; i++){sum = sum + atoi(argv[i]);}printf(“Total sum: %i\n”, sum);return 0;} void printhelp(char progname[]){printf(“%s integer …\n”, progname);printf(“This program takes any number of ”…

$lsfirst-example.c new-sum.c sum.c$cat first-example.c #include <stdio.h>int main(void){printf(“Hello, world!\n”);return 0;}$gcc first-example.c -o first-example$./first-exampleHello, world!$