Using the SEED labs running on Ubuntu 16.04, Please help with the following steps of this task. Thanks! In this task, we study how environment variables are affected when a new program is executed via execve(). The function execve() calls a system call to load a new command and execute it; this function never returns. No new process is created; instead, the calling processs text, data, bss, and stack are overwritten by that of the program loaded. Essentially, execve() runs the new program inside the calling process. We are interested in what happens to the environment variables; are they automatically inherited by the new program?

Step 1. Please compile and run the following program, and describe your observation. This program simply executes a program called /usr/bin/env, which prints out the environment variables of the current process.

#include

#include

extern char **environ;

int main() {

char *argv[2];

argv[0] = "/usr/bin/env";

argv[1] = NULL;

execve("/usr/bin/env", argv, NULL);

return 0 ;

}

Step 2. Change the invocation of execve() in Line to the following; describe your observation. execve("/usr/bin/env", argv, environ);

Step 3. Please draw your conclusion regarding how the new program gets its environment variables.