If a File Extension Is Not in the File Name?

Upload and start working with your PDF documents.
No downloads required

How To Type on PDF Online?

Upload & Edit Your PDF Document
Save, Download, Print, and Share
Sign & Make It Legally Binding

Easy-to-use PDF software

review-platform review-platform review-platform review-platform review-platform

If a file extension is not in the file name, and not because it is hidden, such as a .pdf, how do you determine its file type?

There is a unix tool called file which tries to guess a filename, which you can use in Linux and Windows (e.g. with mingw) that will show you a filetype, which may or may not be correct. Otherwise if it is a video or audio file, rename it to .mp4 and open it with VLC, it will show you what type it actually is if it can detect it. If everything else fails, open the file with a hex editor and try to guess the type, a lot of file types have specific headers or ids, e.g. a PNG file starts with *PNG or GIF starts with GIF89a

PDF documents can be cumbersome to edit, especially when you need to change the text or sign a form. However, working with PDFs is made beyond-easy and highly productive with the right tool.

How to Type On PDF with minimal effort on your side:

  1. Add the document you want to edit — choose any convenient way to do so.
  2. Type, replace, or delete text anywhere in your PDF.
  3. Improve your text’s clarity by annotating it: add sticky notes, comments, or text blogs; black out or highlight the text.
  4. Add fillable fields (name, date, signature, formulas, etc.) to collect information or signatures from the receiving parties quickly.
  5. Assign each field to a specific recipient and set the filling order as you Type On PDF.
  6. Prevent third parties from claiming credit for your document by adding a watermark.
  7. Password-protect your PDF with sensitive information.
  8. Notarize documents online or submit your reports.
  9. Save the completed document in any format you need.

The solution offers a vast space for experiments. Give it a try now and see for yourself. Type On PDF with ease and take advantage of the whole suite of editing features.

Customers love our service for intuitive functionality



46 votes

Type on PDF: All You Need to Know

In Linux, this can be found on the file-extensions line in ls -la and on the name of the file. If the file is not a video or audio, you can try to find out what type it is to help with figuring out what the file might be. Here's a sample (slightly modified) .mp4 video format from /test/. # -f tag = type = video -o out. Raw test.mp4 # -f tag = type = video -o out. Raw /test/ # -a flag = 0 # -I image. Raw out. Raw test/ # -a flag = 0 # -f tag = image. Raw test/ # You can read about the file type in /test/test.mp4, which is actually just a sample of this video (with a couple of extra flags added to the command line): Test.mp4: video/mp4; codecs=”avc1.42E01E, mp4a.40.