Makefile配方的构建时间

Question

I want to caluclate time spent for each recipe in makefile

SYS_TIME = $(shell date)
SUBDIRS = a b c d

.PHONY = default

default:
    for dir in $(SUBDIRS); \
    do \
       $(eval ST = $(SYS_TIME)) \
       $(MAKE) -C FOLD=$$dir; \
       $(eval ET = $(SYS_TIME))
       echo "time spent  =   $(ST) - $(ET) "
   done; \

result should look like:

time spent = 1:35

time spent = 2:23

time spent = 10:59

time spent = 5:35

it signify 1 minute 35 sec for first and same for others

or some other alternative for $(shell date)

Answer 1

只需在命令行前面加上time ，例如： time $(MAKE) -C $$dir 。