How to update book title? - linux

Question

ok.. i'm having trouble with updating new book title.. i've already searched for solutions on this website.. and ive tried them but none of them work..
function update_book
{
#echo "Title: "
read -p $'Title: ' updatetitle
#echo "Author: "
read -p $'Name: ' updatename
if grep -Fq "${updatetitle}:${updatename}" BookDB.txt
then
echo "Book found!"
if ! [ -f BookDB.txt ] ; then
touch BookDB.txt
fi
selection=0
until [ "$selection" = "f" ]; do
echo ""
echo ""
echo "Book Update System"
echo ""
echo ""
echo "a) Update title"
echo "b) Update Author"
echo "c) Update Price"
echo "d) Update Qty Available"
echo "e) Update Qty Sold"
echo "f) Back to main menu"
echo -n "Enter your option: "
read selection
echo ""
case $selection in
a) upd_title;press_enter;;
b) upd_author;press_enter;;
c) upd_price;press_enter;;
d) upd_qty_avail;press_enter;;
e) upd_qty_sold;press_enter;;
f) main_menu;press_enter;;
* ) tput setf 4;echo "Please enter a, b, c, d, e, or f";tput setf 7; press_enter
esac
done
else
echo "Error!! Book does not exist!" #not found
fi
}
ok i've made some changes to the codes for this function.. found out that i should use awk to update from old to new. and use grep to get line number..so it's best i stick with this..
function upd_title
{
read -p 'New title: ' title
#awk '/liine/{ print NR; exit }' BookDB.txt
grep -n 'regex' | sed 's/^\([0-9]\+\):.*$/\1/'
awk 'NR==n{$1=a}1' FS=":" OFS =":" n=$linenumber a = $title BookDB.txt
echo "New title successfully updated!!"
}
but after i tried that code.. this is what i got:
Advanced Book Inventory System
1) Add new book
2) Remove existing book info
3) Update book info and quantity
4) Search for book by title/author
5) Process a book sold
6) Inventory summary report
7) Quit
Enter your option: 3
Title: The Notebook
Name: Nicholas Sparks
Book found!
Book Update System
a) Update title
b) Update Author
c) Update Price
d) Update Qty Available
e) Update Qty Sold
f) Back to main menu
Enter your option: a
New title: Notebook
still doesn't update the title.. >.< anyone can help me point out what's the problem? am i missing something here
help me how to do this.. thanks! :D :D

Answer 1

$updatetitle and $updateauthor defined by the read statements in update_book() are not visible in the upd_title() and other functions you define.
Try exporting them after they are read in. If this doesn't work, pass them in as positional parameters to update_title():
upd_title $update_title $update_author
...
function upd_title
{
update_title=$1
update_author=$2
...
}