execvp - why does my program exit? [duplicate]

Question

I'm executing a program that parses the input to an array and runs function on it. the code is:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>

// arglist - a list of char* arguments (words) provided by the user
// it contains count+1 items, where the last item (arglist[count]) and
//    *only* the last is NULL
// RETURNS - 1 if should cotinue, 0 otherwise
int process_arglist(int count, char** arglist);

void main(void) {
    while (1) {
        char **arglist = NULL;
        char *line = NULL;
        size_t size;
        int count = 0;

        if (getline(&line, &size, stdin) == -1)
            break;

        arglist = (char**) malloc(sizeof(char*));
        if (arglist == NULL) {
            printf("malloc failed: %s\n", strerror(errno));
            exit(-1);
        }
        arglist[0] = strtok(line, " \t\n");

        while (arglist[count] != NULL) {
            ++count;
            arglist = (char**) realloc(arglist, sizeof(char*) * (count + 1));
            if (arglist == NULL) {
                printf("realloc failed: %s\n", strerror(errno));
                exit(-1);
            }      
            arglist[count] = strtok(NULL, " \t\n");
        }

        if (count != 0) {
            if (!process_arglist(count, arglist)) {
                free(line);
                free(arglist);
                break;
            }
        }
        free(line);
        free(arglist);
    }
    pthread_exit(NULL);
}

and my function is:

int process_arglist(int count, char** arglist) {
    int i;
    for (i = 0; i < count; i++) {
        //printf("%s\n", arglist[i]);
        execvp(arglist[0], arglist);
    }
}

when just printed the names (marked), it did not terminate. but when I try to use execvp, it stops after one iteration. Can someone tell me why and what to do?

Answer 1

This is not a bug, it is the way it is supposed to work. execvp replaces the current process with the new process, keeping some of the file handles open.

If you want to launch a new process, you must use fork() and call execvp() in the child process.

Check the man pages for fork() and execvp().