On Sep 14, 4:01pm, Dave Korn wrote: -- Subject: Bizarre behaviour of "make --win32" > > It appears to be using sh.exe, regardless of the --win32 flag. But if I > add stdout redirection to the command in question, it uses cmd.exe. > -- End of excerpt from "Dave Korn"
On non-Cygwin, UNIX platforms, GNU make will optimize away the shell invocation for simple commands, which are identified by lack of known shell metacharacters (like ">"). For example, "foo bar baz" would be executed directly, using something like execvp(), but "foo bar > baz" would run /bin/sh -c "foo bar > baz". If the Makefile sets the SHELL make variable to something other than the default /bin/sh, then this opimization is disabled: GNU make conservatively assumes that it has no idea about the syntax for the nonstandard shell, ignores potential metacharacters, and just always runs $(SHELL) -c "command". This can have performance implications, as you might imagine. I don't know offhand what happens with --win32, but the difference in behavior with stdout redirection that you report is probably related to this optimization. I thought --win32 was supposed to use cmd.exe, but I don't know what the equivalent of execvp() would be for simple commands, or if make --win32 knows about cmd.exe metacharacters. What makes you think that sh.exe is being used? -- Bob -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
