Creates .Xr make 1 meta files when building, which can provide a reliable incremental build when using .Xr filemon 4 . The meta file is created in the OBJDIR as
a target.meta . These meta files track the command ran, its output, and the current directory. When the .Xr filemon 4 module is loaded, any files used by the commands executed will be tracked as dependencies for the target in its meta file. The target will be considered out-of-date and rebuilt if any of the following are true compared to the last build: l -bullet -compact t The command to execute changes. t The current working directory changes. t The target's meta file is missing. t [requires .Xr filemon 4 ] Files read, executed or linked to are newer than the target. t [requires .Xr filemon 4 ] Files read, written, executed or linked are missing. .El The meta files can also be useful for debugging.
p The build will hide commands ran unless .Va NO_SILENT is defined.
p The build operates as it normally would otherwise. This option originally invoked a different build system but that was renamed to .Va WITH_DIRDEPS_BUILD .