How to set multiple values to the same variable in UNIX?

Question

I am trying to have a script give me the output of multiple words and variations of the words. I tried putting in the -o for the variable, quoting the words, piping them together. The words for each varname are the indicated words that I want to have output to me. Is there a way to correct this, or does each variable need to be set individually? Such as varname1=even varname2=Even varname3=EVEN, etc.

#!/bin/bash

varname1=even -o Even -o EVEN
varrname2=odd -o Odd -o ODD
varname3=zero -o Zero -o ZERO
varname4=negative -o Negative -o NEGATIVE

# Ask the user for one of four select words
echo "Type one of the following words:"
echo "even, odd, zero, negative"
read varword
if [[ ("$varword" = $varname1 ) || ("$varword" = $varname2 ) || ("$varword" = $varname3 ) || ("$varword" = $varname4 ) ]]
then
    echo "The approved word you have selected is $varword, great work! "
else
    echo "The unapproved word you have selected is $varword, Please try again."
fi

Answer 1

echo "Type one of the following words:"
echo "even, odd, zero, negative"
while :; do
  read varword
  varword="${varword,,}" #downcase it
  case "$varword" in
    even|odd|zero|negative)
      echo "The approved word you have selected is $varword, great work! "; break;;
    *)
      echo "The unapproved word you have selected is $varword, Please try again.";;
  esac
done

Answer 2

A way to store several values in one variable would be an array. Here is a documentation on how to use array variables in bash.

However, it seems to me that what you want is case insensitive matching. This can be achieved with grep -iq. i tells grep to match case insensitive and q tells grep that it should only return true or false. Also, you can use the or operator \| in the grep clause to match multiple words. Finally you use the herestring notation <<< to feed the variable directly to grep. This simplifies your script considerably:

#!/bin/bash

# Ask the user for one of four select words
echo "Type one of the following words:"
echo "even, odd, zero, negative"
read varword
if grep -iq "even\|odd\|zero\|negative" <<< "$varword"
then
    echo "The approved word you have selected is $varword, great work! "
else
    echo "The unapproved word you have selected is $varword, Please try again."
fi