Once I got a chance to read Archive::Tar module. There is a function named _read_tar. In that function they will read first 512 bytes from the file. They will check whether it contains the GZIP magic number is there in the 512 bytes.

The magic number is a constant defined in Constant.pm inside the Tar directory

I suggest you to go through that module. I feel this information can help you

In reply to Re: How to find out a compressed file inside a script ? by lakshmananindia
in thread How to find out a compressed file inside a script ? by balakrishnan

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