5.3.2 Choosing the Shell------------------------The program used as the shell is taken from the variable `SHELL'.  Ifthis variable is not set in your makefile, the program `/bin/sh' isused as the shell.  The argument(s) passed to the shell are taken fromthe variable `.SHELLFLAGS'.  The default value of `.SHELLFLAGS' is `-c'normally, or `-ec' in POSIX-conforming mode.   Unlike most variables, the variable `SHELL' is never set from theenvironment.  This is because the `SHELL' environment variable is usedto specify your personal choice of shell program for interactive use.It would be very bad for personal choices like this to affect thefunctioning of makefiles.  *Note Variables from the Environment:Environment.   Furthermore, when you do set `SHELL' in your makefile that value is_not_ exported in the environment to recipe lines that `make' invokes.Instead, the value inherited from the user's environment, if any, isexported.  You can override this behavior by explicitly exporting`SHELL' (*note Communicating Variables to a Sub-`make':Variables/Recursion.), forcing it to be passed in the environment torecipe lines.   However, on MS-DOS and MS-Windows the value of `SHELL' in theenvironment *is* used, since on those systems most users do not setthis variable, and therefore it is most likely set specifically to beused by `make'.  On MS-DOS, if the setting of `SHELL' is not suitablefor `make', you can set the variable `MAKESHELL' to the shell that`make' should use; if set it will be used as the shell instead of thevalue of `SHELL'.