While I was treading this assiment I was confuse how to start the assignment since I still confuse with the question what I suppose for this assignment as I am confuse of the instruction and can you also show me how to get the coding into an txt with the cpp and .h in linux?

CSE 4600 Operating Systems Homework #2 All assignments are to be submitted to Canvas. Please note that the due time of homework is at 11:55 pm (Canvas time) on the due date. Please make sure to submit after uploading your files. Please do not attach unrelated files. You will not be able to change your files after clicking submit. When you log onto the Linux lab JB359 computers, the operating system starts running a program called the shell. The standard shell for the Linux operating system running on Linux lab JB359 computers is Bash. The purpose of the shell is to package system services under the control of an interactive command interpreter whose external interface is suitable for human consumption. When the shell program (a passive entity) is run, it becomes a process (an active entity). The shell (process) outputs a command prompt to the screen and then waits to read input entered from the keyboard (i.e., the shell is actually temporarily suspended until you type some characters). After you type some characters and press the return key to end the line, the shell re- starts and reads these characters into an internal array. The shell then analyzes the contents of the internal array to extract commands and arguments. For some commands, such as cd (i.e., change the current directory), the shell can execute the command directly (i.e., the command is built-in to the shell). When the shell finishes executing a built-in command, it outputs another command prompt to the screen. For other commands, such as ls (i.e., list the contents of the specified directory), the shell searches directories specified in the shell path environment variable, looking for a file named ls (type env at the command prompt to see the contents of the path environment variable and other environment variables). If the file is found and the file is executable, the shell will invoke a service of the operating system to run the file, thereby creating a new process. While the shell is waiting for the new process to finish executing, it is temporarily suspended. When the new process finishes executing, the shell re-starts and outputs another command prompt to the screen. A shell program is not really special in any way. In fact, there are actually many different shells available to choose from. And if you dont like any of the available shells, you could write your own given the opportunity and sufficient motivation (e.g., see below). Read some Bash documentation to familiarize yourself with what a shell is, the features a shell provides, and the types of operations a shell support. Some useful documentation can be found by typing man bash at the command prompt. In this homework, you are required to write a shell program, called myshell, that runs on the Linux operating system (specifically, one of the Linux machines in JB359). You can log onto these machines from your Coyote account. PART 1 Implementing myshell and Capturing Result 40 points Your shell program must provide services to support the following commands and features:

2 Note: The commands are shown in uppercase font, but dont have to be programmed that way. The parameters to the commands are enclosed between the symbols < and >, but the symbols are not actually part of the parameters. a. (3 marks) STOP: Terminates execution of the current myshell session. b. (3 marks) SETSHELLNAME : Sets the shell name in the myshell command prompt to . For example, a sample command prompt is shown below: myshell> In this command prompt, there are two parts. The first part, myshell, is the shell name. The second part, >, is the terminator. If no shell name is defined, myshell should be the default shell name. c. (3 marks) SETTERMINATOR : Sets the terminator in the myshell command prompt to . If no terminator is defined, myshell should use > as the default terminator. d. (10 marks) NEWNAME | : Manages the alias list. The first option deletes a previously defined alias. The second option defines an alias for another command. For example, the command NEWNAME mymove deletes the alias for mymove, the command NEWNAME mycopy cp defines mycopy as the alias for the cp command. If an alias for a command already exists, then the new alias replaces the old alias. The maximum number of aliases in the alias list should be set to 10 as the default. e. (6 marks) LISTNEWNAMES: Outputs all the aliases that have been defined. Each pair of names should be shown on one line. For example, the possible aliases for a few commands are shown below: mycd cd mycopy cp f. (6 marks) SAVENEWNAMES : Stores all currently defined aliases in the file . g. (5 marks) READNEWNAMES : Reads all aliases in the file . h. (2 marks) : Executes the UNIX command , corresponding to any valid UNIX command. If the first token on a command line is not a built-in command, assume that it is a UNIX command. i. (2 marks) HELP: shows all built-in commands supported by myshell. Note: You must handle all the built-in commands with exactly the same syntax as shown above. Thus, an important part of the myshell program will be to parse commands entered at the command prompt to break them down into their component parts. Once a command has been parsed, the component parts can be checked to ensure that a valid command has been entered and that it adheres to the required syntax. 2 Note: The commands are shown in uppercase font, but dont have to be programmed that way. The parameters to the commands are enclosed between the symbols < and >, but the symbols are not actually part of the parameters. a. (3 marks) STOP: Terminates execution of the current myshell session. b. (3 marks) SETSHELLNAME : Sets the shell name in the myshell command prompt to . For example, a sample command prompt is shown below: myshell> In this command prompt, there are two parts. The first part, myshell, is the shell name. The second part, >, is the terminator. If no shell name is defined, myshell should be the default shell name. c. (3 marks) SETTERMINATOR : Sets the terminator in the myshell command prompt to . If no terminator is defined, myshell should use > as the default terminator. d. (10 marks) NEWNAME | : Manages the alias list. The first option deletes a previously defined alias. The second option defines an alias for another command. For example, the command NEWNAME mymove deletes the alias for mymove, the command NEWNAME mycopy cp defines mycopy as the alias for the cp command. If an alias for a command already exists, then the new alias replaces the old alias. The maximum number of aliases in the alias list should be set to 10 as the default. e. (6 marks) LISTNEWNAMES: Outputs all the aliases that have been defined. Each pair of names should be shown on one line. For example, the possible aliases for a few commands are shown below: mycd cd mycopy cp f. (6 marks) SAVENEWNAMES : Stores all currently defined aliases in the file . g. (5 marks) READNEWNAMES : Reads all aliases in the file . h. (2 marks) : Executes the UNIX command , corresponding to any valid UNIX command. If the first token on a command line is not a built-in command, assume that it is a UNIX command. i. (2 marks) HELP: shows all built-in commands supported by myshell. Note: You must handle all the built-in commands with exactly the same syntax as shown above. Thus, an important part of the myshell program will be to parse commands entered at the command prompt to break them down into their component parts. Once a command has been parsed, the component parts can be checked to ensure that a valid command has been entered and that it adheres to the required syntax.

3 For this problem, the results are worth 40 marks out of the 50 marks available. The breakdown of these marks is shown above. Demonstrate that your shell works and that it can handle all of the requirements described above. Your demonstration should be captured in a script log file and follow the sequence of commands given below: HELP ls l SETSHELLNAME mysh SETTERMINATOR $ NEWNAME myhelp help NEWNAME mycopy cp NEWNAME mycat cat NEWNAME mydel rm SAVENEWNAMES myaliases.txt LISTNEWNAMES mycat myaliases.txt mycopy myaliases.txt myfile mycat myfile cat myfile ls LISTNEWNAMES READNEWNAMES myaliases.txt STOP PART 2 Error Handling 5 marks Finally, demonstrate that your shell can handle errors. Your shell program should effectively identify and recover from errors. For example, bad input and/or the inability to execute a command should not cause myshell to crash. This will be worth 5 marks out of the 50 marks available. In order to receive all 5 marks, you must be able to handle at least 5 different kinds of errors. Your demonstration should be captured in a script log file. PART 3 Programming Style 5 marks Please use the following style when programming: a. Opening Comment block: there should be comments at the beginning of the program describing Name, ID, the date you write this program. Purpose: what the program does. b. Comment block for member functions: there should be comments before the member function definition describing Purpose: explain what the function does. Parameter(s): explain the purpose of each parameter to the function.

4 Return: if this function sends back a value via a return statement, describe the purpose of that value here. c. Indentation/ spacing: Indenting each subcomponent or statements two or four spaces more than the construct within which it is nested. A single space should be added on both sides of a binary operator. Place braces (i.e., { and }) on separate lines, aligned with one another and the preceding line. d. The descriptive identifiers make programs easy to read. Deliverables: You can work alone or in a partnership. If you are working in a partnership, only one of members of your group submits the assignment to Canvas on behalf of your group. Please add the team members' names and IDs at the opening comment block of source code file hw02.c/cpp. Please submit to Canvas: (1) your source code files hw02.c/cpp (i.e., only the .cpp/c and .h files), (2) a single script log file hw02log.txt showing the correct execution of your shell, and (3) a single script log file hw02errorlog.txt showing the error handling capabilities of your shell.