Question

Supposedly I have this line in my text file which has the following format.

"Title:Author:Price:QtyAvailable:QtySold"

The contents of my text file is shown below

 Hello World:Andreas:10.50:10:5
 Lord Of The Rings:Duke:50.15:50:20
    (some other records...)

1) User inputs Author and Title.

2) If Program locates the Author+Title, it asks user to Update any of the fields available ( for this case Title, Author, Price etc..

3) For example I will like to update the Price of Hello World book.

4) What can I do to tell the program to extract the contents of the Hello World line, and get into 10.50 to replace the price of the book? (assumes new price of the book will be decided by the user’s input)

Hope to get my answer.
Thanks in advance to those who helped!

Answer 1

Following is a something to get you started:

Sample Script:

[jaypal:~/Temp] cat s.sh 
#!/bin/bash

echo "Author?"
read author

echo "Title?"
read title

grep -c "$title:$author" file > /dev/null # Look for a line with matching values

if [ $? == 0 ]; then # If found then offer to change price
    echo "I found the book, Do you want to update price to what?"
    read newprice
    sed -i "s/\($book:$author\):[^:]*:/\1:$newprice:/" file
fi

Input Data:

[jaypal:~/Temp] cat file
Hello World:Andreas:10.50:10:5
Lord Of The Rings:Duke:50.15:50:20

Execution:

[jaypal:~/Temp] ./s.sh 
Author? 
Andreas
Title? 
Hello World
I found the book, Do you want to update price to what?
40
[jaypal:~/Temp] cat file
Hello World:Andreas:40:10:5
Lord Of The Rings:Duke:50.15:50:20