更聪明，更精简的方法来匹配Shell脚本中的输入变量？

Question

I have a file with a list of numerous unique items, for this example I am using user ID's. The starting section of my script should display the list to the user running the script and allow them to chose one of the ID's. The script should then cross check the choice made by the user against the original file and if it matches it should provide a message advising of the match and continue with the script. If it does not match, the script should advise the user and exit.

My current script does this OK, but I was wondering if there is any way to make it a bit smarter/more condensed, perhaps using arrays? Current script:

This is my first post on this site so I apologies in advanced for any mistakes which have been made in the process of posting.

FILE=testfile
IDLIST="$(awk '{print $1}' $FILE)"
echo "$IDLIST"
echo "\nSelect one of the options"
read input
OUTPUT="$(for i in $IDLIST
          do
               if [[ $i = $input ]]
                    then
                    echo "Matched."
               fi
          done)"

if [[ -z $OUTPUT ]]
    then
    echo "Invalid choice."
    exit 0
    else
    ID=$input
fi

echo "It is a match, continuing with script"

Answer 1

As you can imagine, there are many ways of doing this. One is using select instead:

PS3="Select an ID: "
select id in $(cut -d ' ' -f 1 testfile)
do
  [[ -z $id ]] && echo "Pick a number" || break
done
echo "You selected $id"