An [attribute expression](<https://hpc.lenovo.com/users/user_reference/attributeexpressions/index.md>) will contain some directives wrapped in {} characters.

When using `nodeattrib` substitution there might be the temptation to do substitution of username and passwords which will not work.

### Example

when using `noderun` attribute expressions for bmcuser and bmcpass will not work, this is expected behavior.

```
noderun <nodename> ipmitool -I lanplus -U "{bmcuser}" -P {bmcpass} -H {bmc}
```

```
Password:
n1052: Error: Unable to establish IPMI v2 / RMCP+ session
```

The inability to use attribute expressions for passwords is expected behavior for security reasons. Allowing this functionality would allow passwords and username to be echoed in plain text