installing esp32 boards in arduino ide in a linux environment
open terminal $ sudo apt-get update
$ sudo apt-get install python
$ sudo apt-get install python-pip
$ sudo pip install pyserial
go to File> prefernces>in that find additional bords copy and paste the below link https://dl.espressif.com/dl/package_esp32_index.json, http://arduino.esp8266.com/stable/package_esp8266com_index.json
then try installing the board