Collect a bunch of command outputs in a shell script and send to Instrumental, no dependencies

cmd-instrumental.sh

#!/bin/sh
if [ -z "$1" ]
then
  echo "You have to pass your Instrumental API token as an argument to this script."
  exit -1
fi
instrumental_token=$1

# List of keys and commands to run for them
declare -a measurements=(
  # KEY                                           # COMMAND
  "size_of_foo_list"                              'redis-cli --raw llen foolist'
  "just_the_number_5"                             'echo 5'
)
map_size=`expr ${#measurements[@]} - 1`

# Instrumental outgoing packet
hello="hello version 1.0\n"
authenticate="authenticate ${instrumental_token}\n"

packet=$hello$authenticate
for idx in `seq 0 2 ${map_size}`
do
  key=${measurements[$idx]}
  cmd=${measurements[`expr ${idx} + 1`]}
  result=`${cmd}`
  rc=$?
  if [[ $rc != 0 ]]
  then
    echo "Failed to exec" $cmd
    exit $rc
  fi
  packet="${packet}gauge ${key} ${result}\n"
done
if [[ -n "$DEBUG" ]]
then
  echo $packet
fi
echo $packet | nc collector.instrumentalapp.com 8000

Should be noted that the command outputs should be numbers and nothing else

I should note that this sort of script would likely be executed via a cron job