12.13 The obj/ Subdirectory and Make

Never name one of your subdirectories obj/ if you don't like surprises.

If an obj/ directory exists, BSD make enters it before reading the makefile. Hence the makefile in the current directory is not read.

     $ cat Makefile
     all:
             echo Hello
     $ cat obj/Makefile
     all:
             echo World
     $ make      # GNU make
     echo Hello
     Hello
     $ pmake     # BSD make
     echo World
     World