how to run file if folder exists in linux code example

Example 1: linux command if directory exists

DIR="/etc/httpd/"
if [ -d "$DIR" ]; then
  ### Take action if $DIR exists ###
  echo "Installing config files in ${DIR}..."
else
  ###  Control will jump here if $DIR does NOT exists ###
  echo "Error: ${DIR} not found. Can not continue."
  exit 1
fi

Example 2: zsh check if file exists

FILE=/etc/resolv.conf
if [[ -f "$FILE" ]]; then
    echo "$FILE exists."
fi