README.md

Exercises

Instructions and shell script here assumes bash shell. Tested on GNU bash, version 4.3.46

• For example, the first exercise for GNU_grep
  • directory: ex01_basic_match
  • question file: ex01_basic_match.txt
  • solution reference: .ref_solutions/ex01_basic_match.txt
• Each exercise contains one or more question to be solved
• The script solve will assist in checking solutions

$ git clone https://github.com/learnbyexample/Command-line-text-processing.git
$ cd Command-line-text-processing/exercises/GNU_grep/
$ ls
ex01_basic_match      ex02_basic_options      ex03_multiple_string_match      solve
ex01_basic_match.txt  ex02_basic_options.txt  ex03_multiple_string_match.txt

$ find -name 'ex01*'
./.ref_solutions/ex01_basic_match.txt
./ex01_basic_match
./ex01_basic_match.txt

• Solving the questions
  • Go to the exercise folder
  • Use ls to see input file(s)
  • To see the problems for that exercise, follow the steps below

$ cd ex01_basic_match
$ ls
sample.txt

$ # to see the questions
$ source ../solve -q
1) Match lines containing the string: day


2) Match lines containing the string: it


3) Match lines containing the string: do you


$ # or open the questions file with your fav editor
$ gvim ../$(basename "$PWD").txt
$ # create an alias to use from any ex* directory
$ alias oq='gvim ../$(basename "$PWD").txt'
$ oq

• Submitting solutions one by one
  • immediately after executing command that answers a question, call the solve script

$ grep 'day' sample.txt 
Good day
Today is sunny
$ source ../solve -s
---------------------------------------------
Match for question 1:
Submitted solution: grep 'day' sample.txt 
Reference solution: grep 'day' sample.txt
---------------------------------------------

• Submit all at once
  • by editing the ../$(basename "$PWD").txt file directly
  • the answer should replace the empty line immediately following the question
• Note
  • there are different ways to solve the same question
  • but for specific exercise like GNU_grep try to solve using grep only
  • also, remember that eval is used to check equivalence. So be sure of commands submitted

$ cat ../$(basename "$PWD").txt
1) Match lines containing the string: day
grep 'day' sample.txt

2) Match lines containing the string: it
sed -n '/it/p' sample.txt

3) Match lines containing the string: do you
echo 'How do you do?'

$ source ../solve
---------------------------------------------
Match for question 1:
Submitted solution: grep 'day' sample.txt
Reference solution: grep 'day' sample.txt
---------------------------------------------
---------------------------------------------
Match for question 2:
Submitted solution: sed -n '/it/p' sample.txt
Reference solution: grep 'it' sample.txt
---------------------------------------------
---------------------------------------------
Match for question 3:
Submitted solution: echo 'How do you do?'
Reference solution: grep 'do you' sample.txt
---------------------------------------------
		All Pass		

• Then move on to next exercise directory
• Create aliases for different commands for easy use, after checking that the aliases are available of course

$ type cs cq ca nq pq
bash: type: cs: not found
bash: type: cq: not found
bash: type: ca: not found
bash: type: nq: not found
bash: type: pq: not found

$ alias cs='source ../solve -s'
$ alias cq='source ../solve -q'
$ alias ca='source ../solve'
$ # to go to directory of next question
$ nq() { d=$(basename "$PWD"); nd=$(printf "../ex%02d*/" $((${d:2:2}+1))); cd $nd ; }
$ # to go to directory of previous question
$ pq() { d=$(basename "$PWD"); pd=$(printf "../ex%02d*/" $((${d:2:2}-1))); cd $pd ; }

If wrong solution is submitted, the expected output is shown. This also helps to better understand the question as I found it difficult to convey the intent of question clearly with words alone...

$ source ../solve -q
1) Match lines containing the string: day


2) Match lines containing the string: it


3) Match lines containing the string: do you

$ grep 'do' sample.txt 
How do you do?
Just do it
No doubt you like it too
Much ado about nothing
$ source ../solve -s
---------------------------------------------
Mismatch for question 1:
Expected output is:
Good day
Today is sunny
---------------------------------------------