Bash wrapper using `column` for nicely formatted listing of SSH keys

list-SSHkeys.sh

#!/usr/bin/env bash

#Wrapper around ssh-add -l
#to show available Keys in properly formatted way
#and to optionally output as json

#Function getKeys() to get Keys in -l format with SHA256 sums or as  key signature with -L
#Call by getKeys -keySigFormat[sha256|key]
function getKeys() {
    [[ $keySigFormat == "sha256" ]] && ssh-add -l
    [[ $keySigFormat == "key" ]]    && ssh-add -L
}

function genOutput() {
    case $keySigFormat in
        "sha256") getKeys $keySigFormat | column -t -O 3,2,4,1 -N"Key-Length","SHA256Sum","File","Key-Type" $jsonFlag ;;
        "key") getKeys $keySigFormat | column -t -O 3,1,2 -E2 -T2 -N"Key-Type","Key","File" $jsonFlag ;;
    esac

}

function help(){
cat <<EOF
-h|-?|--help           Get this help
--keysig [sha256|key]  Chose format to show Keysignature in.
                       SHA256 or actual key. Defaults to SHA256
--json                 Output as JSON
EOF
}

keySigFormat="sha256"
jsonFlag=""

while test $# != 0; do
    case $1 in
      -h|-?|--help) help ; exit ;;
      --keysig) keySigFormat=$2 ;;
      --json) jsonFlag=-J ;;
    esac
    shift
done

genOutput