Using bash variables in Makefile - bash

Question

I want to use the bash timing variables in my makefile
for example in my terminal I can do this and it works
MY_TIME=$SECONDS
echo $MY_TIME
but when I write this on my makefile it does not work
how can I use these two lines in my make file?
this is what I'm doing
.PHONY: myProg
myProg:
MY_TIME=$SECONDS
echo $MY_TIME
After Etan Reisner' answer
This is what I have now
.PHONY: myProg
myProg:
MY_TIME= date; echo $MY_TIME
but the result of my echo is an empty line, it does not look like it is storing the date

Answer 1

the dollar sign ($MY_TIME) refers to make variables, which are not the same as bash variables.
To access a bash variable you must escape the dollar using the double dollar notation ($$MY_TIME).
.PHONY: myProg
myProg:
MY_TIME=$$SECONDS ; echo $$MY_TIME
As already mentioned in Etan answer you can't split the code into multiple lines (unless you are using the backslash) since each command executes in a different subshell, making variables inaccessible to other lines.
In the following example the value of SECONDS will be always 0, since it get reset by the spawn of the shell for the second line.
.PHONY: myProg
myProg: # WRONG
MY_TIME=$$SECONDS
echo $$MY_TIME

Answer 2

By default make uses /bin/sh as the shell which executes recipe lines.
Presumably /bin/sh doesn't support the SECONDS variable.
You can tell make to use a different shell by assigning a value to the SHELL variable (i.e. SHELL := /bin/bash).
Doing that will make SECONDS available but will still not allow you to carry a variable value between recipe lines as each recipe line is run in its own shell.
So to do what you want you would need to write both of those lines on one line or continue the line over the newline.
.PHONY: myProg
myProg:
MY_TIME=$SECONDS; echo $MY_TIME
or
.PHONY: myProg
myProg:
MY_TIME=$SECONDS; \
echo $MY_TIME
That being said you would almost certainly be better off not doing this and instead using something like date invoked at the start/end of the recipe or time invoked on the command to be timed directly instead.
.PHONY: myProg
myProg:
date
# Do something
date
or
.PHONY: myProg
myProg:
time some_command

Answer 3

PROGRAM_NAME = myLittleProgram
...
$(PROGRAM_NAME) : myLittleProgram.o
I know the above works, as it is in my own makefile (program names and object names changed to protect the innocent).
"Variable references can be used in any context: targets, dependencies, commands, most directives, and new variable values. Here is an example of a common case, where a variable holds the names of all the object files in a program:"
objects = program.o foo.o utils.o
program : $(objects)
cc -o program $(objects)
$(objects) : defs.h
http://web.mit.edu/gnu/doc/html/make_6.html