Added comments

Lesson04/Exercise 18/Exercise 18.txt

@@ -2,6 +2,8 @@
  # Make sure you are in the ~/Lesson4 folder
 
  # Step 1 to 3 - write following script (all the lines upto but not including Step 4) and save to pgn_extract1.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 
 #!/usr/bin/env bash 
 regex_blank="^[[:space:]]*$" 

Lesson04/Exercise 19/Exercise 19.txt

@@ -15,6 +15,7 @@ function read_chunk()
 
 
  # Step 2 to 6 - Write script and save to pgn_extract2.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 7 

Lesson04/Exercise 20/Exercise 20.txt

@@ -3,6 +3,7 @@
 
 
  # Step 1 to 3 - Write script and save to pgn_extract3.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 4
@@ -24,6 +25,7 @@
 
 
  # Step 6 & 7 - Modify pgn_extract3.sh by adding the following and save as pgn_extract4.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 function show_nth_game()
 {

Lesson04/Exercise 21/Exercise 21.txt

@@ -3,6 +3,8 @@
 
 
  # Step 1 to 2 - Write following function in editor, save as pgn_extract5.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 
 function filter_game()
 {
@@ -39,6 +41,8 @@ done
 
 
  # Step 6 to 8 - save following code as pgn_extract6.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 function read_moves()
 { 
   moves=''
@@ -63,6 +67,8 @@ echo "$moves"
 
 
  # Step 10 to 11 - Add following code to pgn_extract6.sh and save as pgn_extract7.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 
 function count_moves()
 {
@@ -85,6 +91,8 @@ done
 
 
  # Step 13 to 22 - Add following code to pgn_extract7.sh and save as pgn_extract8.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 function filter_game()
 {
   # Initially assume not found
@@ -125,6 +133,8 @@ function show_games_won_in()
 
 
  # Step 25 - Combine pgn_extract4.sh and pgn_extract8.sh into pgn_extract_final.sh 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 ./pgn_extract_final.sh -m 8 <games.pgn
 ./pgn_extract_final.sh -n 231 <games.pgn
 

Lesson04/Exercise 22/Exercise 22.txt

@@ -30,14 +30,18 @@ trip_duration '2017-10-10 12:00:00' '2017-10-10 00:00:00'
 
 
  # Step 6 - Edit the last line of the above function as the following and save it as taxi1.sh
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 echo $(( ((n_stop - n_start) + 86400) % 86400 ))
 
 
  # Step 7
 ./taxi1.sh '2017-10-10 12:00:00' '2017-10-10 00:00:00'
 
 
- # Step 8 - No typing
+ # Step 8 - Create the taxi2.sh script as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
+
 
 
  # Step 9
@@ -46,28 +50,32 @@ head -n5 nyc_taxi.csv
 ./taxi2.sh <nyc_taxi.csv | head -n10 
 
 
- # Step 10 - No typing
+ # Step 10 - Create the taxi3.sh script by modifying taxi2.sh as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 11
 ./taxi3.sh <nyc_taxi.csv | head -n10 
 
 
- # Step 12 - No typing
+ # Step 12 - Create the taxi4.sh script as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 13
 time head -n5000 nyc_taxi.csv | ./taxi4.sh >test.txt 
 
 
- # Step 14 - No typing
+ # Step 14 - Create the taxi5.sh script as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 15
 time head -n5000 nyc_taxi.csv | ./taxi5.sh >test.txt 
 
 
- # Step 16, 17 - No typing
+ # Step 16, 17 - Create the taxi6.sh script as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 18

Lesson04/Exercise 23/Exercise 23.txt

@@ -6,7 +6,8 @@
  head -n5 test.txt
 
 
- #Step  2 to 5 - No Typing
+ #Step  2 to 5 - Create the taxi7.sh script as per the lesson 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 6

Lesson04/Exercise 24/Exercise 24.txt

@@ -1,7 +1,8 @@
 #  Taxi Trip Analysis - Calculating Fare
 #  Make sure you are in the ~/Lesson4 folder
 
- # Step 1,3 - Create the taxi8.sh script as per lesson
+ # Step 1,3 - Create the taxi8.sh script as per lesson - 
+ # Before moving to the next step, remember to run the command chmod u+x on it to make it executable
 
 
  # Step 4