builtin.sh is installed as a set of tools to stand in for specific filesystem call to builtin commands. for example if /bin/test is used, then builtin.sh will be loaded and simply call the builtin function of the same name. At this moment it is installed as the following commands: /bin/[ /bin/command /bin/echo /bin/expr /bin/getopts /bin/read /bin/test /bin/umask /bin/wait If one of the following is replaced by the NetBSD equivalent, please update the list, and remove this completly when it is not anymore required.