Add a value to an environmental variable while avoiding putting an unnecessary colon.

add_env_with_colon.sh

# Add a value to an environmental variable while avoiding putting an unnecessary colon.
# Usage: add_env_with_colon PATH $HOME/local/bin

function add_env_with_colon {
  ENV_VAR_NAME=$1
  VALUE_TO_ADD=$2
  CURRENT_VALUE=${!ENV_VAR_NAME}
  if [ -n "$CURRENT_VALUE" ]; then
    export $ENV_VAR_NAME=$VALUE_TO_ADD:$CURRENT_VALUE
  else
    export $ENV_VAR_NAME=$VALUE_TO_ADD
  fi
}