I've been checking whether which files of some open source components are used during compile. But, I don't know well about autotools, autoconf, etc.. so, I want to know the "auto" value means in AC_ARG_ENABLE(). Here is an example.
AC_ARG_ENABLE(launchd, AS_HELP_STRING(--description--),enable_launchd=$enableval,enable_launchd=auto)
If "--enable-launchd" option is given, run the command "enable_launchd=$enableval", right?? But if not, run the command "enable_lauchd=auto". What is a value of the "auto"?
If "--enable-launchd" option is given, run the command "enable_launchd=$enableval", right??
Right.
But if not, run the command "enable_lauchd=auto".
Yes.
What is a value of the "auto"?
"auto" has no significance in that command other than as itself. It is the value assigned to variable enable_launchd.
You may well find that configure.ac later checks for that value and performs additional processing if it is seen, or you might find that it just emits it as-is into an external file.