[SOLVED] NSYSP Homework 2

Part 1

1. Edit the parse.c file to use strtok() and realloc( ) to implement the parse() and free_argv()

functions.

2. Files provided: shell.h shell.c parse.c
3. Example:

Part 2

1. Add code to the builtin.c stub to recognize the echo, quit, exit, logout and bye commands. Write functions implementing these commands, and add a new line for

each command to table inbuilts[] just above the line {NULL, NULL}.

2. File provided:

Builtin.c

3. echo example:

echo print all strings echo -n N: print the specified string

4. quit example: exit, quit, logout and bye terminate the program.

Part 3

1. Edit the run_command.c file so a child process is created to run the command, and the parent waits for the child process to terminate. Check for builtin commands first, create a new process only for commands which are not built in. Use the parser from pervious labs to create from the command line the argv array passed to the child.

Hint: You can use exec()/execvp() function, waitpid() function and the fork() system call.

2. File provided: run_command.c 3. Example:

Part 4

1. Edit the is_background.c file to detect an “&”. Alter the run_command.c file so that if a task is running in the background, the parent does not wait. Do not worry about

background processes becoming zombies at this point; this will be addressed later.

2. File provided: is_background.c 3. Example: