bash: trim leading & trailing whitespace chars in a variable

trim.sh

#!/usr/bin/env bash

# Function definitions
# --------------------

# trim leading & trailing whitespace chars
trim() {
  local var="$1"
  var="${var#"${var%%[![:space:]]*}"}" # trim leading whitespace chars
  var="${var%"${var##*[![:space:]]}"}" # trim trailing whitespace chars
  echo -n "$var"
}

# Script begin
# ------------

# get variables
datetime1="$(adb shell date +%s)"

# trim variables
datetime1_trimmed="$(trim "${datetime1}")"

# print out for debug
echo "datetime1=[${datetime1}]"
echo "datetime1_trimmed=[${datetime1_trimmed}]"