Unix bash cutting and grep

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/bashecho "Title:"read title# shopt -s nocasematch           # if you want case-insensitive matchingwhile 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]}"        fidone < input.txt

The next step up from grep and cut is awk. Unless you must do this using bash (is this homework?), then awk would make things considerably easier:

awk -F: '/harry potter/ { sub(/^/,"$",$(NF-2)); print }' IGNORECASE=1 OFS=", " db.txt

Test input:

Harry Potter and the Sorcerer's Stone:J.K. Rowling:21.95:100:200Harry Potter and the Chamber of Secrets:J.K. Rowling:21.95:150:300Lord of the Rings, The Fellowship of the Ring:J.R.R. Tolkien:32.00:500:500A Game of Thrones:George R.R. Martin:44.50:300:250

Test output:

Harry Potter and the Sorcerer's Stone, J.K. Rowling, $21.95, 100, 200Harry Potter and the Chamber of Secrets, J.K. Rowling, $21.95, 150, 300

read -p "Enter title: " TITLEwhile IFS=: read title author price x y; do    if [[ ${title,,} == *${TITLE,,}* ]]; then        printf "%s, %s, $%s, %s, %s\n" "$title" "$author" "$price" "$x" "$y"    fidone < db.txt

The test in the if command does a simple glob-match but case insensitively, so it will match if the user enters "potter".

Or, use sed to change the separators:

read -p "Enter title: " TITLEsed '/'"$TITLE"'/I!d; s/:/, /g' db.txt

which means delete all lines that do not match the TITLE, then transform the separator.