Please make sure you have read the Tag Syntax document and understand how tag attribute syntax works.
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/file-description.html %}
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/file-attributes.html %}
<s:file name="anUploadFile" accept="text/*" /> <s:file name="anohterUploadFIle" accept="text/html,text/plain" />