linux腳本來更新價格

Question

我想做一個代碼，提示用戶輸入一本書的標題和作者，我想使用grep來獲取基於標題和作者的數據並回顯爲用戶可以查看和編輯的價格，而無需用戶輸入舊價格

我需要在試圖獲得$價格變量的幫助就可以通過輸入標題和作者

function update_cost 
{ 
    echo "Title: " 
    read title 
    echo "Author: " 
    read author 
    grep -iqs "$title:$author:$price:" BookDB.txt && echo "$title:$author:$price:" 
    echo "New Price: " 
    read price_r 
    sed -i "/^$title:$author:/ s/$price/$price_r" BookDB.txt || tee BookDB.txt && echo "Book Price has been updated sucessfully!" 
} 

Answer 1

關於上述問題，我想出了一個答案。希望它可以幫助

price=$(echo "$result" | cut -f 3 -d ":") 

我設法得到一個什麼樣的，結果行，然後使用sed的線路匹配它的用戶輸入我編輯的第三場第三場。

function update_cost 
{ 
    echo "Enter Title: " 
    read title 
    echo "Enter Author: " 
    read author 
    result=$(grep -ise "$title\:$author" BookDB.txt) 
    price=$(echo "$result" | cut -f 3 -d ":") 
    grep -iqs "$title:$author:$price:" BookDB.txt && echo "Book Found!"  
    echo "New Price: " 
    read new_price 
    sed -i "/^$title:$author:$price:/ s/$price/$new_price/" BookDB.txt || tee BookDB.txt && echo "Price has been updated sucessfully!" 

} 

Answer 2

awk更適合從文件中提取一個字段並將其分配給一個變量。

function update_cost 
{ 
    echo "Title: " 
    read title 
    echo "Author: " 
    read author 
    price=$(awk -F: -v title="$title" -v author="$author" '$1 == title && $2 == author { print $3 }' BookDB.txt) 
    echo "Old price is $price" 
    echo "New Price: " 
    read price_r 
    sed -i "/^$title:$author:/ s/:$price:/:$price_r:/" BookDB.txt || tee BookDB.txt && echo "Book Price has been updated sucessfully!" 
}