How to read multiple variables from a file

Question

Example File

oj Orange Juice

10 100

A half gallon of orange juice.

This is what I did and it worked

while read -r simpleName itemName; do
        read currentQuantity maximumQuantity
        read description
    echo "Item Name: $itemName"
    echo "Simple Name: $simpleName"
    echo "Item Number: $itemNumber"
    echo "Qty: $currentQuantity/$maximumQuantity"
    echo "Description: $description"
done < $FILE

Note: Item number is prompted from the user prior to this and it determines which file to open.

This while loop correctly reads the file, stores the variables, and gives the desired output. The issue is, I used this same exact while loop two more times and it's not working. For some reason in the other two scenarios, simpleName and itemName are coming up blank, but the rest are working correctly.

Here's an example of where it is NOT working

#!/bin/bash
echo ""
read -p "Enter an item number: " itemNumber
echo ""
FILE="./data/${itemNumber}.item"
date=date "+%Y-%m-%d %H:%M:%S"
if test -f $FILE; then
if test -f ./data/queries.log; then
    echo "DELETED: $date - $simpleName" >> ./data/queries.log
else
    > ./data/queries.log
    echo "DELETED: $date - $simpleName" >> ./data/queries.log
fi

while read -r simpleName itemName; do
    read currentQuantity maximumQuantity
    read description
done < $FILE

rm $FILE

echo "$simpleName was successfully deleted."

else
    echo "ERROR: item not found."
fi

Here, the output comes out incorrectly as

was successfully deleted

So $simpleName is blank for some reason. I can't figure out why it works in the first instance but not this instance.

Note: Both instances are within separate script files.

I'm aware that there are simpler ways to do things, however, I'm restricted to very very basic commands, I am not allowed to use sed, awk, grep, find, pretty much just what you see below.

Answer 1

read always assigns values to the variables, even if it doesn't see the expected delimiter and hence exits with a falsy status.

E.g.

$ (var=abcdef; 
   echo "      var=\"$var\"";
   read var;
   echo "ret=$? var=\"$var\"") < /dev/null
      var="abcdef"
ret=1 var=""

See also the idiom for processing a final incomplete line in a while read loop too: What does `while read -r line || [[ -n $line ]]` mean?

So, when you have this:

while read -r simpleName itemName; do
    read currentQuantity maximumQuantity
    read description
done < $FILE

a three-line input will first load all the variables, then try to read to simpleName and itemName again, trashing them. Or course this would also read the whole file, and e.g. a four-line input will leave all the variables empty.

I'm not sure what you want to do here, but perhaps something like this:

while    read -r simpleName itemName
      && read currentQuantity maximumQuantity
      && read description; do
    process one set of values ...
done < "$FILE"