ComSpec

ComSpec, officially referred to as the COMSPEC environment variable, designates the path to the command-line interpreter on Windows and DOS systems. It is used by the operating system and many applications to locate the program that should be used to run command-line processes. COMSPEC is inherited by child processes, enabling scripts and utilities to spawn a shell without hardcoding a specific executable.

In modern Windows installations based on the Windows NT lineage, COMSPEC typically points to the command processor CMD.EXE, usually located in the System32 directory, for example C:\Windows\System32\cmd.exe. Historically, in DOS and Windows 9x environments, COMSPEC pointed to COMMAND.COM, the native command interpreter of those systems.

The variable is commonly accessed by users and software to determine how to invoke a command shell. For example, a script or program may reference the path stored in COMSPEC to launch a new command interpreter with arguments such as /c to execute a command and then terminate. It is also viewable at a command prompt with a query like echo %COMSPEC%, or retrieved through system APIs that expose environment variables.

Although altering COMSPEC is possible through system environment settings, changing it can affect scripts, installers, and utilities that rely on a stable reference to the command processor. Therefore, modifications are generally discouraged unless there is a specific operational need.

See also: environment variables, CMD.EXE, COMMAND.COM.