quarchk.cmd

Windows command script Reference

A .cmd file contains a batch script for the Windows command interpreter, cmd.exe. The plain-text file lists commands that run in order. Scripts automate tasks such as builds, copies, and service control. The extension .bat marks the same script type from the MS-DOS era. Both extensions run in the same interpreter on Windows.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.