We can now try to encrypt a value on the command line using the Jerakia transit key and the policy that we've just created:
$ echo -n "Lorem ipsum dolor sit amet" | base64 | ./vault write transit/encrypt/jerakia plaintext=- -policy=jerakia
vault:v1:Xv3R5CugxnCLhL/T2eJ+rN+UilHzo78evxd0tf5efx0M2U2qIgaI
See the Vault documentation for more specifics on the read and write commands: https://www.vaultproject.io/docs/commands/read-write.html.