Data processing pipeline example

This can be used to motivate and teach Makefiles.

Examples

Process one file:

$ cat data/lorem.in | ./count.py | ./plot.py

Process all files:

$ make [-jN]

Makefile

SRCS = $(wildcard data/*.in)

OBJS = $(patsubst %.in,%.tmp,$(SRCS))
OBJS += $(patsubst %.in,%.out,$(SRCS))

all: $(OBJS)

# otherwise intermediate tmp files would be deleted
.PRECIOUS: %.tmp

%.tmp: %.in
	cat $< | ./count.py > $@

%.out: %.tmp
	cat $< | ./plot.py > $@