Quick Sort in Makefile

qsort.mk

#!/usr/bin/gmake -sf
#modified after jserv's Makefile.qsort from
#http://blog.linux.org.tw/~jserv/archives/002035.html

gt = $(shell if [ $1 -gt $2 ] ; then echo TRUE; fi)
lt = $(shell if [ $1 -lt $2 ] ; then echo TRUE; fi)
le = $(shell if [ $1 -le $2 ] ; then echo TRUE; fi)
define qsort
$(if $(call le,$(words $1),1),$1, \
 $(call qsort, \
  $(foreach i,$1, \
   $(if $(call gt,$(firstword $1),$i), $i,))) \
 $(firstword $1) \
 $(call qsort, \
  $(foreach i,$1, \
   $(if $(call lt,$(firstword $1),$i), $i,))))
endef
ifeq "$(MAKECMDGOALS)" ""
$(info Usage: qsort.mk num1 num2 num3 ...)
else
$(info $(strip $(call qsort, $(MAKECMDGOALS))))
endif

%:
	@true