Unix bash cutting and grep

Question

I have a text file called db.txt. Some sample lines from the file goes as such:

Harry Potter and the Sorcerer's Stone:J.K. Rowling:21.95:100:200

Harry Potter and the Chamber of Secrets:J.K. Rowling:21.95:150:300

Lord of the Rings, The Fellowship of the Ring:J.R.R. Tolkien:32.00:500:500

A Game of Thrones:George R.R. Martin:44.50:300:250

Then in my script, I have the following lines:

echo "Enter title:"
read TITLE

cut -d ":" -f 1 db.txt | grep -iw "$TITLE" | while read LINE
do
    STRING="`echo $LINE | cut -d ":" -f 1`,"
    STRING="$STRING `echo $LINE | cut -d ":" -f 2`, "
    STRING=" \$$STRING`echo $LINE | cut -d ":" -f 3`,"
    STRING=" $STRING`echo $LINE | cut -d ":" -f 4`,"
    STRING=" $STRING`echo $LINE | cut -d ":" -f 5`"
done

Is there a way to grep a specific field from cut and then pass in the full line into the while loop?

For example, if I entered "Harry Potter", it should display:

Harry Potter and the Sorcerer's Stone, J.K. Rowling, $21.95, 100, 200

Harry Potter and the Chamber of Secrets, J.K. Rowling, $21.95, 150, 300

Answer 1

You can do this without cut, and without grep if you're ok with bash's regular expression matching (or can use shell pattern matching instead).

The idea would be to read the file line by line, then split the line into an array. Once you've got that, do the comparisons and output you want.

Here's a demo of the technique:

#! /bin/bash
echo "Title:"
read title

# shopt -s nocasematch           # if you want case-insensitive matching

while read line ; do             # this read takes data from input.txt, see
                                 # end of loop
        IFS=: read -a parts <<< "$line"  # this splits the line on ":" into
                                         # an array called parts

        if [[ ${parts[0]} =~ $title ]] ; then  # regex matching
                printf "%s -- %s\n" "${parts[1]}" "${parts[2]}"
        fi
done < input.txt