ansible-vault-pass

ansible-vault-pass.sh

use the technique described in http://docs.ansible.com/ansible/latest/config.html#default-vault-password-file

create a file: vault-pass.sh

cat > vault-pass.sh << EOF
#! /bin/bash
echo $ANSIBLE_VAULT_PASSWORD
EOF

chmod +x vault-pass.sh

export ANSIBLE_VAULT_PASSWORD='yourpassword'
export ANSIBLE_VAULT_PASSWORD_FILE=/vault-pass.sh

now try:
ansible-vault view encrypted.yml