Homework & Coursework Questions

1. The problem statement, all variables and given/known data:
So i'll probably get told off for this but I have a few problems and rather than clog up the whole forum I'll post them here. Please bare in mind I am a complete novice when it comes to all this and so if you help please treat me like a complete idiot

I have a text file of names and test scores called class.txt e.g.

Code:

Bob Smith 15
James Jones 25
Emily Hunt 70

Then another text file with more detail called classdetails.txt e.g. (note the subject, date, first and surname, class, scores are separated by tabs, also the names are one field not two)

Code:

Maths     10/05/12     Bob Smith     Class 5      65:54:32:96
English   15/04/12     James Jones   Class 7      84:64:83:38
Science   12/07/13     Emily Hunt    Class 9      73:28:95:07

Then finally a text file called test.txt that simply contains

qwertyuiop

I have done half of the exercise and am really struggling with the rest of the questions. We are told to use awk from the command line,


6)Print all of the contents of the file (class.txt) and give a title to each column and separate out each column with a tab, send he output to another file.

7)Print out all of the students who have scored over 30 and redirect the output to sort to display alphabetically.

8)Print out all of the students and redirect the output to sort to display in order of their score.

9)Use colrm on a copy of the file test.txt to remove the last column.

10)Use colrm on a copy of the file test.txt to remove columns 3 to 5.

11)Print “testing” five times using awk.

12)Using the classdetails.txt file print col 5 and then sort the output in numerical order. Note this file is tab separated - hint use sort to sort the output from awk.

13)Create 4 files with the suffix .txt in your home directory. Create a sub-directory. Using awk and the UNIX shell move all of the .txt files to the sub-directory.


2. Relevant commands, code, scripts, algorithms:

I have a very basic knowledge of things like awk, grep, sort and pipes but other than that I'm clueless.

3. The attempts at a solution (include all code and scripts):

To print all of the contents of the file I have tried

Code:

awk ‘{print}' class.txt > class2.txt

and then perhaps edit the file with nano although I'm sure there is a better way.

Question 7 I imagine is largely similar to 6 except instead of the " > class2.txt" perhaps something involving pipes ??

Question 8 the same as above except using pipes to sort i.e. | sort -l

Question 9 and 10 I have no clue about colrm so again any help appreciated.

Question 12 will be similar to 6 I think

Question 13 No clue.

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):

Northern Illinois University, DeKalb (IL), United States, Raymond Ege, CSCI330


Note: Without school/professor/course information, you will be banned if you post here! You must complete the entire template (not just parts of it).

Welcome to the forums.. Some pointers:

@6) for printing titles:read up on the purpose of the BEGIN{} section in awk. I doubt editing with nano will be accepted
@7) sounds good
@8) read up on the various sort command line options ("man sort")
@9 and 10) see "man colrm"

Really helpful mate, thanks a lot

touch is the command that you can use to create the files.
mkdir the sub-dir
pipe a name list of the 4 .txt files using something like ls to awk and sh

It is unusual to use awk for this, but since it looks that it is focus on piping, here's a clue

Code:

ls *.txt | awk '{print "ls -l", $0} | sh

question 6 is basically adding a header. you can use a special block called a BEGIN block in awk to to do. for example awk 'BEGIN { print "name\tid"; } 1 { print $0; }' class.txt

You've not shown much work on the rest.

awk works with fields. You seem to understand how to change the field separator. If you want to print every record where column 5 is greater than 30, you'd use something like awk '$5 > 30'

awk code follows the syntax condition { action }. The default condition is 1 (or always true) and the default action is print $0. Thus, the above example is equivalent to awk '$5 > 30 { print $0 }'.

Have a look at man sort and you will see how to sort on certain fields as well. Make sure to use -n for numeric sort where needed.

The questions involving making a directory and moving files shouldn't require awk. awk is a text processor. Unless those files are to be made with certain text or are part of the other questions output... In the shel you'd use mkdir and mv to make a directory and move files, respectively.

Moderator's Comments:

This post was originally submitted to a duplicate thread.