This is a small tool we wrote to assist validators in generating a bunch of pem files given a mnemonic.
$ npm install -g @elrondnetwork/elrond-pem
$ elrond-pem generate-mnemonic # You will be prompted to choose a path, ex: ./my-secrets/mnemonic.txt
$ elrond-pem generate-pems 10 0 0 # The parameters used are: numberOfPems, accountIndex, addressIndex
$ # You will be prompted to enter a path to a file containing your mnemonic, then a path to the output folder.
$ git clone https://github.com/ccorcoveanu/secret-encoder.git && cd secret-encoder
$ node ./index.js generate-mnemonic
$ node ./index.js 10 0 0