Final answer:
To search for a specific file type, use the filetype command followed by the desired file extension (pdf, doc, txt).
Step-by-step explanation:
To search for a specific file type, you can use the file type command followed by the desired file extension.
For example, if you want to search for PDF files, you can use filetype:pdf. If you want DOC files, you can use filetype:doc. And for TXT files, you can use filetype:txt.