Task: Mini Shell

As you might remember, to create a new process you need to use fork (or clone) and exec system calls. If you don’t, take a look at what happens under the hood when you use system.

Enter the labs/lab-07/tasks/mini-shell directory, open the support/src folder and go through the practice items below.

Use the tests/checker.sh script to check your solutions.

./checker.sh
mini_shell: ls ................ passed ... 50
mini_shell: pwd ................ passed ... 25
mini_shell: echo hello ................ passed ... 25
100 / 100

  1. With this knowledge in mind, let’s implement our own mini-shell.

    Start from the skeleton code in mini_shell.c. We’re already running our Bash interpreter from the command-line, so there’s no need to exec another Bash from it.

    Simply exec the command.

    Quiz

    So we need a way to “save” the mini_shell process before exec()-ing our command. Find a way to do this.

    Hint: You can see what sleepy does and draw inspiration from there. Use strace to also list the calls to clone() performed by sleepy or its children. Remember what clone() is used for and use its parameters to deduce which of the two scenarios happens to sleepy.