1. Make a variable, called mypython that contains the path to Python on your machine. You shouldn’t need to manually type the path.
2. Construct a variable that has the value <username>@<machinename> using existing environment variables and the hostname utility.

3. Figure out how to use the mkdir command to create the following directory structure in one short command:

   temp
   ├── proj1
   │   ├── code
   │   └── data
   ├── proj2
   │   ├── code
   │   └── data
   └── proj3
       ├── code
       └── data
   

4. How would you count the number of lines in an input file, say a data file.
5. Print the first three lines of a file to the screen. Now print just the third line to the screen.
6. Put the third line of a file in a new file.
7. Now add the fifth line of the file to that same file from the previous problem.
8. Extract the Australia data from the cpds.csv dataset and put it in a file called cpds_australia.csv. It’s OK if you do this in a straightforward way and it might fail if ‘Australia’ is present in an unexpected column.
9. Find all the lines in a file that do not contain a comma. (You might use this to look for anomalies in a CSV file.)
10. Write shell code that creates files file1.txt, file2.txt, file3.txt, etc., with the word ‘blah’ as the only line in each file.

11. Write shell code that modifies each file from the previous problem so that the number 1, 2, 3, etc. is prepended to the appropriate file (i.e., there is a new first line in each file that simply contains the number corresponding to the file name).

    You may want to write the code to do this operation on a single file before embedding the code in the loop.

12. Create a shell function that will run a Python job in the background such that I can run the job by typing:

    $ bpy file.py file.out
    

    You can create a test jobs with: echo -e 'a=5\nprint(a)' > file.py

13. Modify the function so that you can simply type :

    $ bpy file.py
    

    and it will use file.pyout as the output file.

14. Use ps to print out all the processes on the machine with information on memory and CPU use and sort the output of ps in decreasing order of memory use.
15. Take $mypython from the first problem and strip the python off the end—assigning the result to a new variable, path_to_py.