BASH：从数组中设置变量的最佳方法

Question

Bash 4 on Linux ~
I have an array of possible values. I must restrict user input to these values.

Arr=(hello kitty goodbye quick fox)

User supplies value as argument to script:

bash myscript.sh -b var

Currently, I'm trying the following:

function func_exists () {
_var="$1"
for i in ${Arr[@]}
do
    if [ "$i" == "$_var" ]
    then
        echo hooray for "$_var"
        return 1
    fi
done
    return 0
}

func_exists $var
if [ $? -ne 1 ];then
    echo "Not a permitted value."
    func_help
    exit $E_OPTERROR
fi

Seems to work fine, are there better methods for testing user input against an array of allowed values?

UPDATE: I like John K's answer...can someone clarify the use of $@? I understand that this represents all positional parameters -- so we shift the first param off the stack and $@ now represents all remaining params, those being the passed array...is that correct? I hate blindly using code without understanding...even if it works!

Answer 1

function func_exists () {
  case "$1"
  in
    hello)
    kitty)
    goodbye) 
    quick)
    fox)
      return 1;;
    *)
      return 0;;
  esac
}

Answer 2

Your solution is what I'd do. Maybe using a few more shell-isms, such as returning 0 for success and non-0 for failure like UNIX commands do in general.

# Tests if $1 is in the array ($2 $3 $4 ...).
is_in() {
    value=$1
    shift

    for i in "$@"; do
        [[ $i == $value ]] && return 0
    done

    return 1
}

if ! is_in "$var" "${Arr[@]}"; then
    echo "Not a permitted value." >&2
    func_help
    exit $E_OPTERROR
fi

Careful use of double quotes makes sure this will work even if the individual array entries contain spaces, which is allowed. This is a two element array: list=('hello world' 'foo bar') .

Answer 3

Another solution. is_in is just a variable:

Arr=(hello kitty goodbye quick fox)

var='quick'

string=" ${Arr[*]} "                            # array to string, framed with blanks
is_in=1                                         # false
# try to delete the variable inside the string; true if length differ 
[ "$string" != "${string/ ${var} /}" ] && is_in=0

echo -e "$is_in"