Systems Programming Assignment 1: Shell Scripting Solution

For this assignment, you will use bash create a simple course catalog for administrators to update the details of each course offered by their department. The system will store basic information about each course, allowing the user to create, read, update, and delete them.




This assignment requires only the utilities used so far in the lecture notes. Do not use sed, awk, or any programming languages or utilities not yet covered in the lecture notes.




Tip: Filenames in the native Linux filesystem are case-sensitive. Thus, without proper consid-eration, a course whose associated filename was created as cs3423.crs (based on lowercase input given for the course’s department code the time of its creation) will not also be associated with the file CS3423.crs. This is not desirable behavior, however, as user’s may unexpectedly enter either uppercase or lowercase department codes when using your script.




Therefore, you may utilize a bash feature (known as “case modification” parameter expansion) that enables you to easily convert the contents of a variable to its uppercase equivalent. For example, this feature can be utilized to produce the capitalized contents of the variable containing a depart-ment code by simply writing ${dept_codeˆˆ} instead of $dept_code when building the filename you will use for a particular course.




Tip: Note, that when prompted to enter a department code and course number, you should enter these values as two separate tokens separated by a space. Otherwise, it would be necessary to perform complex token-splitting to separate these values, which is outside the scope of this assignment. For example, when prompting the user:




Enter a department code and course number:




You should enter “cs 3423”, not “cs3423”!




Storing Course Information







Course information will be stored in text files.




Files will be stored inside a directory called data within the same directory as your script.



Each file will be named based on the combination of a department code and a course number, which consists of two or three letters followed by an integer with exactly four digits, followed by the extension .crs (notice that the text file does not end in .txt. Does that need to be accounted for?).



A course file consists of exactly five lines:



dept_code (two or three letter abbreviation) dept_name (string with probable whites-pace)



course_name (string with probable whitespace)






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course_sched (string consisting precisely of either “MWF” or “TH”) course_start (string with no whitespace) course_end (string with no whitespace)



course_hours (credit hours, unsigned integer)



course_size (enrolled students, unsigned integer)



* Department names may contain whitespace. You should account for names with multiple tokens (e.g., “ESL English as a Second Language” =⇒ dept_code = “ESL”, and dept_name = “English as a Second Language”)




Example file named esl3053.crs






ESL English as a Second Language Literacy in a Second Language MWF 8/26/19 12/13/19




3




52










Script Execution







When the script is run, the following should occur. All script output should appear exactly as it appears below.




Upon running your script, the user should be presented with the following menu:



Enter one of the following actions or press CTRL-D to exit. C - create a new course record




R - read an existing course record U - update an existing course record D - delete an existing course record




E - update enrolled student count of existing course T - show total course count




The user then enters a one-character action (upper or lowercase), leading to one of the follow-ing.



C: a course is created



From the terminal, read the following one at a time:



Department code (two-to-three character string)



Department name (string possibly containing whitespace)



Course number (integer)



Course name (string possibly containing whitespace)



Course schedule (string ∈ {MWF, TH})



Course start date (string with slashes)



Course end date (string with slashes)






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Course credit hours (unsigned integer)



Initial course enrollment (unsigned integer)



Using the values entered by the user, create a new file in the data folder based on the instructions above.



Update data/queries.log by adding the following line:



[date ] CREATED: dept_code course_num course_name




where date is the output from the date command and dept_code, course_num, and course_name are the corresponding values.




If the course already exists, print the following error and continue with the script. The script should accept all seven inputs before checking if the record exists.



ERROR: course already exists




R: read an existing course’s information



Prompt the user for a course department and course number: (e.g., “cs 3423”)



Enter a department code and course number:




Search for the specified course using the provided department and number (e.g., “cs 3423”).



Print the course information in the following format:



Course department: dept_code dept_name




Course number: course_num




Course name: course_name




Scheduled days: course_sched




Course start: course_start




Course end: course_end




Credit hours: course_hours




Enrolled Students: course_size




If the course is not found, print the following error instead and continue with the script.
ERROR: course not found




U: update an existing course record



Prompt the user for the following one at a time:



Department code (two-to-three character string)



Department name (string possibly containing whitespace)



Course number (integer)



Course name (string possibly containing whitespace)



Course meeting days (string ∈ {MWF, TH})



Course start date (string with slashes)



Course end date (string with slashes)






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Course credit hours (unsigned integer)



Course enrollment (unsigned integer)



Search for the specified course using the course department and course number (e.g., “cs 3423”).



Update each of the corresponding fields based on the user input. If the user input is blank for a particular field, keep the original value from the file.



Update data/queries.log by adding the following line:



[date ] UPDATED: dept_code course_num course_name




where date is the output from the date command and dept_code, course_num, and course_name are the corresponding values.




If the course is not found, print the following error and continue with the script. The script should accept all nine inputs before checking if the record exists.
ERROR: course not found




D: delete an existing course



Prompt the user for a string representing the course department and number (e.g., “cs 3423”):
Enter a course department code and number:




Delete the specified course’s file.



Update data/queries.log by adding the following line:



[date ] DELETED: dept_code course_num course_name




where date is the output from the date command and dept_code, course_num, and course_name are the corresponding values.




Print the following message to stdout with the course’s number: course number was successfully deleted.



If the course is not found, print the following error instead and continue with the script.
ERROR: course not found




E: update the number of enrolled students for an existing course



Prompt the user for a string representing the course department and number (e.g., “cs 3423”):
Enter a course department code and number:




Prompt the user for an enrollment change amount (e.g., entering a value of 3 would represent enrolling three new students in the class, while -2 would reflect two students having dropped the course):
Enter an enrollment change amount:




Search for the specified course using the course number.



Update the course record by adding the new enrollment count to the course’s current enrollment count. Negative values are allowed. (i.e., students could drop the



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class).




Update data/queries.log by adding the following line:



[date ] ENROLLMENT: dept_code course_num course_name changed by change_amt




where date is the output from the date command and dept_code, course_num, course_name, and change_amt are the corresponding values.




If the course record is not found, print the following error and continue with the script. The script should accept the enrollment change amount before checking if the record exists.
ERROR: course not found




T: print the total number of course records



Print the total number of .crs files within the data directory:



Total course records: total where total is the total .crs files.




If an invalid character is entered, print the following error and continue with the script.



ERROR: invalid option




After an action is completed, display the menu again. This should go on indefinitely until CTRL-D or the end of a file is reached.



Assignment Data







An initial data set can be found in /usr/local/courses/ssilvestro/cs3423/Fall19/assign1.




Copy this to your own assignment’s directory.







Script Files







Your program should consist of seven bash files with the following names (case sensitive):




assign1.bash - the main file which is initially invoked



create.bash - logic for the create option



read.bash - logic for the read option



update.bash - logic for the update option



delete.bash - logic for the delete option



enroll.bash - logic for the update enrollment option



total.bash - logic for the total option
























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Verifying Your Program







Your program must work with the input provided in a1Input.txt. To test it:




Verify that your assignment folder has a data directory with the initial data set.



Execute your script and redirect a1Input.txt into it. You should not be copying or typing the contents of a1Input.txt into your terminal. Redirection must work.



Verify that the output and files are as expected.






Submission







Turn your assignment in via Blackboard. Your zip file, named abc123.zip (with your personal abc123) should contain only your seven bash files.























































































































































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