My program only works when I declare an extra array - c

Question

I'm building a simple shell for a class. There are two programs in my shell directory, called "alomundo" and "echo". "./alomundo" prints "Alo mundo!" to console, and ./echo executes the ubuntu echo with given args.
The thing is my program only works if I declare the char aux[15]. Notice I don't use it aux for nothing. Can anyone understand whats wrong?
An example input would be
./shell echo a b, alomundo, echo abc
The correct output is
a b
Alo mundo!
abc
The output when char aux[15] is not declared is just:
Alo mundo!
abc
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
char aux[15]; // <---- GRRRR
int child; // will hold the childs PID after fork()
int i = 0; // counter to loop through this mains *argv[]
int t = 0; // auxiliar counter to loops
int arg_len; // will hold the length of each argument while the argument is being processed
int args = 0; // current number of arguments in the argv1 vector
int send = 0; // boolean to check if the command should be executed in the current loop or not
char *command; // string to hold the main command name
char *argv1[15]; // vector to hold the arguments passed to execve
for(i=1; i<argc; i++) {
arg_len = strlen(argv[i]);
argv1[args] = (char *) malloc(sizeof(char) * 25);
for(t=0; t<25; t++) {
argv1[args][t] = '\0';
}
if (argv[i][arg_len-1] == ',') {
argv[i][arg_len-1] = '\0';
send = 1;
}
else if (i == (argc-1)) {
send = 1;
}
if (args == 0) {
command = (char *) malloc(sizeof(char) * 255);
strcpy(command, "./");
strcpy(argv1[args], "./");
strcat(command, argv[i]);
}
strcat(argv1[args], argv[i]);
args++;
if (send) {
child = fork();
if (child == 0) {
argv1[args+1] = 0;
execve(command, &argv1[0], envp);
return 0;
}
else {
waitpid(child);
free(command);
for (t=0; t<args; t++) {
free(argv1[t]);
argv1[t] = NULL;
}
args = 0;
send = 0;
}
}
}
return 0;
}

Answer 1

waitpid(child) seems wrong. Try:
// ...
#include <sys/wait.h>
// ...
pid_t child;
int wstatus;
// ...
else {
wait(&wstatus);
envp is not declared. Try:
// ...
int main(int argc, char *argv[], char *envp[]) {
// ...
Off-by-one error in argv1 processing. Try:
// ...
if (child == 0) {
argv1[args] = 0;
execve(command, argv1, envp); // why use &argv1[0] ?
// ...
I think (3) is the culprit.
Compiling with different levels of optimisation (-O, etc) seems to affect whether or not the erroneous +1 causes a problem.