CODEWITHSUNDEEP
makefile
robintw
robintw

Reputation: 28591

Printing variable from within Makefile

I have the following code in my makefile:

S_RES=$(shell cat output)

echo -e "Serial result = \t" $(S_RES)

Basically, I want to store the output of the shell command cat output in the S_RES variable, and then echo that variable to the screen (with some explanatory text in front of it). I also want to be able to use the variable later on in my program. I thought I had followed the instructions given in various StackOverflow questions, but it doesn't seem to work.

Upvotes: 23

Views: 50101

Answers (2)

alex
alex

Reputation: 71

just a side note

this evaluates on use time, this is as many times as $(A) is used

A = something

this evaluates on parse time, thus the value is evaluates once

A := something

Upvotes: 7

Ise Wisteria
Ise Wisteria

Reputation: 11669

If simple space instead of escape sequence \t is allowed, and your make is GNU make 3.81 or higher, $(info) is available.
For example:

$(info Serial result = $(S_RES))

If your make's version is 3.80 or lower, $(warning) might meet the purpose. However, warning prints line number etc. too.

EDIT: For your information, the following makefile outputs abc on my GNU make 3.81.

A := $(shell echo abc)
$(info $(A))

Upvotes: 44

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