Quiz 2: fork, exec, and environment variables

Write a C program that forks two processes that print command-line arguments and environment variables.

Before your start coding, you can briefly read about environment variables in Linux here: https://www.geeksforgeeks.org/environment-variables-in-linux-unix/

Each process should echo all its command-line arguments and its entire environment list.

Parent process

The parent process should:

• Print its process ID

First child process

The first process should:

• Print its process ID
• Call the echoall executable using execle, which requires a pathname and a specific environment.
  • execle should pass two arguments to echoall that are: "Bandicoot" and "Pacman".
  • execle should use the custom environment variables provided in custom_env.

Second child process

The second process should:

• Print its process ID
• Call the echoall executable using execlp, which uses a filename.
  • execlp should pass one argument to echoall that is: "Spyro".
  • The caller’s environment is automatically passed to the new program.

Important notes:

1. For execlp to work, the path to the executable program echoall should be in your system path. Read about how to set your $PATH variable in Linux at https://opensource.com/article/17/6/set-path-linux.
2. Another reference for adding $PATH: https://zwbetz.com/how-to-add-a-binary-to-your-path-on-macos-linux-windows/
3. You can create a directory bin and add /home/your_username/bin/ to your path.
4. For both exec calls, set the first argument, argv[0] in the new program, to be the filename component of the pathname.
5. We provided the program echoall.c that should be executed by both processes. Compile echoall.c and move the executable to a directory in your $PATH.
6. Refer to the sample output expected_output.txt as an example