exec() not working with firefox

https://stackoverflow.com/questions/4481001

11-10-2019
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Question

I've been using a combination of fork() and exec() to execute some external command on linux, however, the code seems to fail whenever I try to execute /usr/bin/firefox which is a symbolic link to a real binary.

Does anyone know how to solve this problem? I've tested with other programs (which really are executable binaries and not symlinks to them) and it works.

Here's the code from the program:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>
#include <errno.h>

int main(int argc, char **argv) {
  pid_t pid;
  // this was the old line:
  // char *parmList[] = {"", "index.html", NULL};
  // and this is the one that solves the problem:
  char *parmList[] = {"firefox", "index.html", NULL};
  int a;

  if ((pid = fork()) == -1)
    perror("fork failed");

  if (pid == 0) {
    a = execvp("/usr/bin/firefox", parmList);
    fprintf(stdout, "execvp() returned %d\n", a);
    fprintf(stdout, "errno: %s (%d).\n", strerror(errno), errno);
  }
  else {
    waitpid(pid, 0, 0);
  }

  return 0;
}

Edit: I updated the code to include the answer and changed the topic's title because the problem really didn't seem to be due to symbolic links at all. Thanks everyone.

Solution

You might want to add some code right after the execvp to output some diagnostic (i.e. check errno, print something meaningful ;)).

You could also try to analyze it w/o source modification using strace or gdb for that matter.