Practice Questions

Question 1

In COMP 1002, you have successfully built your personal webpage when you learned about Reading and Changing Permissions of files. We are now going to automate a few of those processes in building (or updating) your personal webpage. For this, we are going to write a shell script to automate the conversion from markdown to HTML and also to change the permissions of the generated HTML file.

1. Let us convert the file from markdown to HTML. Name your script as publish_webpage. The script should take the name of the markdown file as parameter and convert it to HTML using pandoc. For example, if your markdown file is index.md, you would run it as:

   ./publish_webpage index.md

2. Now, we need to change the permissions of the recently generated file index.html. Recall that the permissions are:

   • index.html:
     • User must have read and write, but no execute permission.
     • Group must have read, but no write nor execute permissions.
     • Other must have read, but no write nor execute permissions.

Question 2

Now, we improve the shell script publish_webpage from Question 1.

Input Error Prevention

Imagine that you shared your script with a friend but they did not check your implementation. The idea here is to prevent that your friend type an incorrect name as the argument of publish_webpage. For this, before performing any action in the script publish_webpage, check if the file passed on the command line by the user actually exists. If the file do not exist, print to standard output “File not found!” using echo command. Otherwise, print “File found!” and execute the rest of the script. If you need to recal the file operators you can check the section on Structures: conditional statements and loops.

Question 3

Using a glob to find all the zip files in a directory, write a shell script called unzipall that uses a for loop to iterate over all the zip files, then use unzip to extract the files from the compressed format.

Let’s test the unzipall script. For this, we need a few zip files to extract. Download the following file using the wget command:

https://university-of-manitoba-computer-science.github.io/tools-n-techniques/topic09/to_extract.zip

Extract the downloaded to_extract.zip file. Then, you will have five other zip files. Use the script unzipall you have written to extract all the compressed files. If you need help, the section on Compiling and running code shows how to use wget and how to use unzip to extract compressed zip files.