echo : /usr/src/bin/echo/echo.c /usr/include/stdio.h \
  /usr/include/sys/types.h /usr/include/machine/endian.h \
  /usr/include/sys/cdefs.h /usr/include/machine/ansi.h \
  /usr/include/machine/types.h /usr/include/stdlib.h /usr/include/string.h 
