Bash prompt function

gistfile1.sh

_prompt() {
    local _prompt=$1
    local _out=$2
    local _default=$3
    local _val=''
    if [ $_default ]; then
        _prompt="${_prompt} [${_default}]"
    fi  
    read -p "$_prompt " _val
    if [ $_val ]; then
        eval $_out="'$_val'"
    else
        eval $_out="'$_default'"
    fi  
}

# Usage: _prompt "Question?" TARGET_VARNAME ["default"]
# For example:

_prompt "What is your name?" NAME "Steve"
# What is your name? [Steve] _
echo $NAME  # "Steve" or whatever the user entered.

_prompt "Pick a number." NUMBER
# Pick a number. _