It's hardly possible to use all expression of the Simple language to create file names in the file component

<route id="fileReader">
    <from uri="file://rootFolder?move=.backup&amp;moveFailed=.error/${header.CustomHeader}" />
    <to uri="file://out"/>
</route>

/**
 * Bind this GenericFile to an Exchange
 */
public void bindToExchange(Exchange exchange) {
    exchange.setProperty(FileComponent.FILE_EXCHANGE_FILE, this);
    GenericFileMessage<T> in = new GenericFileMessage<T>(this);
    exchange.setIn(in);
    populateHeaders(in);
}

/**
 * Populates the {@link GenericFileMessage} relevant headers
 *
 * @param message the message to populate with headers
 */
public void populateHeaders(GenericFileMessage<T> message) {
    if (message != null) {
        message.setHeader(Exchange.FILE_NAME_ONLY, getFileNameOnly());
        message.setHeader(Exchange.FILE_NAME, getFileName());
        message.setHeader("CamelFileAbsolute", isAbsolute());
        message.setHeader("CamelFileAbsolutePath", getAbsoluteFilePath());

        if (isAbsolute()) {
            message.setHeader(Exchange.FILE_PATH, getAbsoluteFilePath());
        } else {
            // we must normalize path according to protocol if we build our own paths
            String path = normalizePathToProtocol(getEndpointPath() + File.separator + getRelativeFilePath());
            message.setHeader(Exchange.FILE_PATH, path);
        }

        message.setHeader("CamelFileRelativePath", getRelativeFilePath());
        message.setHeader(Exchange.FILE_PARENT, getParent());

        if (getFileLength() >= 0) {
            message.setHeader("CamelFileLength", getFileLength());
        }
        if (getLastModified() > 0) {
            message.setHeader(Exchange.FILE_LAST_MODIFIED, new Date(getLastModified()));
        }
    }
}