Question reference: Â Refer to Chapter 1 Exercise 1.6 to determine the result after invoking the changeColor() method of the circular object and entering the color without quotes.

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Whentheuserenters!!,themostrecentcommandinthehistoryisexecuted.In the example above, if the user entered the command: Osh> !! The ‘ls -l’ command should be executed and echoed on user’s screen. The command should also be placed in the history buffer as the next command. Whentheuserentersasingle!followedbyanintegerN,theNthcommandin the history is executed. In the example above, if the user entered the command: Osh> ! 3 The ‘ps’ command should be executed and echoed on the user’s screen. The command should also be placed in the history buffer as the next command. Error handling: The program should also manage basic error handling. For example, if there are no commands in the history, entering !! should result in a message “No commands in history.” Also, if there is no command corresponding to the number entered with the single !, the program should output "No such command in history."

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Chapter 1, Problem 6E

Program Plan Intro

Question reference:Â Refer to Chapter 1 Exercise 1.6 to determine the result after invoking the changeColor() method of the circular object and entering the color without quotes.

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Whentheuserenters!!,themostrecentcommandinthehistoryisexecuted.In the example above, if the user entered the command: Osh> !! The ‘ls -l’ command should be executed and echoed on user’s screen. The command should also be placed in the history buffer as the next command. Whentheuserentersasingle!followedbyanintegerN,theNthcommandin the history is executed. In the example above, if the user entered the command: Osh> ! 3 The ‘ps’ command should be executed and echoed on the user’s screen. The command should also be placed in the history buffer as the next command. Error handling: The program should also manage basic error handling. For example, if there are no commands in the history, entering !! should result in a message “No commands in history.” Also, if there is no command corresponding to the number entered with the single !, the program should output "No such command in history."

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2. UNIX Shell and History Feature [20 points] This question consists of designing a C program to serve as a shell interface that accepts user commands and then executes each command in a separate process. A shell interface gives the user a prompt, after which the next command is entered. The example below illustrates the prompt osh> and the user's next command: cat prog.c. The UNIX/Linux cat command displays the contents of the file prog.c on the terminal using the UNIX/Linux cat command and your program needs to do the same. osh> cat prog.c The above can be achieved by running your shell interface as a parent process. Every time a command is entered, you create a child process by using fork(), which then executes the user's command using one of the system calls in the exec() family (as described in Chapter 3). A C program that provides the general operations of a command-line shell can be seen below. #include #include #define MAX LINE 80 /* The maximum length command */ { int…