If you've tried to use keytool on windows OS you've probably saw bunch of errors such as keytool is not recognized, even if you add keytool to the path you need to restart your PC and yet there is no guarantee for it to work or not showing you another errors.

Here I'm showing you how to use keytool without environment path or restarting your computer.

First go to following location

C:\Program Files\Android\Android Studio\jre\bin

Next open your terminal run as administrator and then type following command

keytool -export -rfc -alias <YOUR_ALIAS_NAME> -file upload_certificate.pem -keystore <LOCATION_OF_YOUR_KEYSTORE_FILE>\keystore.jks

Now all you need to do is to change placeholder part of command above to your desire locations.

After changing placeholder parts and hitting Enter, you'll be asked for keystore file password and your .PEM file will be generated at C:\Program Files\Android\Android Studio\jre\bin, you can copy/cut it to another folder if you want to.

Congratulation you've made update file by keytool.