PostScript / EPS file signature
Magic number at the start of the file · %!PS
PostScript and Encapsulated PostScript are text programs that start with %!PS. An EPS with a binary TIFF or WMF preview instead begins with the DOS EPS header C5 D0 D3 C6, which points to the PostScript further in.
What this magic number means
A magic number is a short, fixed run of bytes at a known position that tells a program what a file really is, no matter what the filename says. If a file starts with the bytes 25 21 50 53 (the text %!PS), it is a PostScript / EPS file.
Signature variants
PostScript / EPS appears with more than one byte pattern. These all identify the same family:
| Hex signature | Offset | Note |
|---|---|---|
| 25 21 50 53 | 0 | ASCII PostScript, %!PS |
| C5 D0 D3 C6 | 0 | DOS EPS binary header (preview attached) |
Formats that use the 25 21 50 53 signature
These file types in our database carry this signature:
How to check a file's signature
You can read the first bytes of any file yourself. The magic bytes are shown in hex, the same way this page lists them.
Linux & macOS
- xxd -l 16 example.eps
- hexdump -C -n 16 example.eps
- file example.eps
Windows (PowerShell)
- Format-Hex -Path example.eps -Count 16
Python
- open("example.eps","rb").read(4).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the PostScript / EPS file signature?
PostScript / EPS files start with the hex bytes 25 21 50 53 (%!PS in ASCII). This magic number identifies the format regardless of the file's name or extension.
How do I check a file's magic number?
Open the file in a hex editor, or run a command such as xxd -l 16 example.eps on Linux or macOS, or Format-Hex -Path example.eps -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the PostScript / EPS signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine PostScript / EPS file has these exact bytes; a file with the wrong bytes is not really PostScript / EPS, whatever its name says.