How To Link Permissions

To link an existing permission, submit a transaction to the linkauth action of the eosio account.

In the example shown below useraaaaaaaa links the permission action_perm to the contract useraaaaaaaa's contract_action action.

const linkauth_input = {
  account: 'useraaaaaaaa',      // the permission's owner to be linked and the payer of the RAM needed to store this link
  code: 'useraaaaaaaa',         // the owner of the action to be linked
  type: 'contract_action',      // the action to be linked
  requirement: 'action_perm',   // the permission to be linked

(async () => {
  await api.transact({
    actions: [{
      account: 'eosio',
      name: 'linkauth',
      authorization: [{
        actor: 'useraaaaaaaa',
        permission: 'active',
      data: linkauth_input,
  }, {
    blocksBehind: 3,
    expireSeconds: 30,