多个单词作为bash中的可能变量

Question

The line Hi=("Hi" "Hello" "Hey") has the possible inputs. I've tried adding a comma between the words and that does not work either. If hi , hello , or hey are typed in, I need it to echo "Hi". Right now only Hi works. I guess what I'm looking for is a way to make "synonyms" for a word. The ability to substitute a one word for another.

    clear; echo
    shopt -s nocasematch
    echo; read -p "    > " TextInput

    Hi=("Hi" "Hello" "Hey")

     if [[ "$TextInput" == $Hi ]]; then
    clear; echo; echo
    echo -e "    >> Hi"
    echo

     else
    clear; echo; echo
    echo -e "    >> Error"
    echo
    fi

I know I could use

     if [[ "$TextInput" == "Hi" ]] || [[ "$TextInput" == "Hello" ]] || [[ "$TextInput" == "Hey" ]]; then

but that will get to be way too long.

Answer 1

If your target is bash 4.0 or newer, an associative array will work:

TextInput=Hello
declare -A values=( [Hi]=1 [Hello]=1 [Hey]=1 )

if [[ ${values[$TextInput]} ]]; then
  echo "Hi there!"
else
  echo "No Hi!"
fi

This is an O(1) lookup, making it faster than an O(n) loop-based traversal.

---

That said, if the list of items you're matching against is hardcoded, just use a case statement:

case $TextInput in
  Hi|Hello|Hey) echo "Hi there!" ;;
  *)            echo "No Hi!     ;;
esac

This also has the advantage of being compatible with any shell compliant with POSIX sh.

Answer 2

Take a look at this variant:

TextInput="Hello"
Hi=("Hi" "Hello" "Hey")

flag=0

for myhi in ${Hi[@]}; do
    if [[ "$TextInput" == "$myhi" ]]; then
        flag=1
        break
    fi
done

if [[ $flag == 1 ]]; then
    echo "Hi there!"
else
    echo "No Hi!"
fi

The thing is: use a flag + a for loop. If the flag is set (=1), then the TextInput is equal to something in your Hi array.

Answer 3

Depending on your needs, you can also use a switch:

case "$input" in
  "Hi"|"He"*)
    echo Hello
    ;;
  *)
    echo Error
    ;;
  esac

This allows you to also specify patterns.

Answer 4

Using bash's pattern matching:

$ Hi=(Hi Hello Hey)
$ input=foo
$ if (IFS=:; [[ ":${Hi[*]}:" == *:"$input":* ]]); then echo Y; else echo N; fi
N
$ input=Hey
$ if (IFS=:; [[ ":${Hi[*]}:" == *:"$input":* ]]); then echo Y; else echo N; fi
Y

I use parentheses here to spawn a subshell, so changes to the IFS variable don't affect the current shell.