How to get pid of my make command in the Makefile?

Question

I want to use a temp directory that will be unique to this build. How can I get the pid of my make command in the Makefile?

I tried:

TEMPDIR = /tmp/myprog.$$$$

but this seems to store TEMPDIR as /tmp/myprog.$$ and then eval as a new pid for every command which refs this! How do I get one pid for all of them (I'd prefer the make pid, but anything unique will do).

Thanks in advance.

Answer 1

Try mktemp for creating unique temporary filenames. The -d option will create a directory instead of a file.

TEMPFILE := $(shell mktemp)
TEMPDIR := $(shell mktemp -d)

Note the colon. (Editor's note: This causes make to evaluate the function once and assign its value instead of re-evaluating the expression for every reference to $(TEMPDIR).)

Answer 2

make starts a new shell for each command it starts. Using bash (didn't check for other shells) echo $PPID gives the parent process ID (which is make).

all: subtarget 
        echo $$PPID
        echo $(shell echo $$PPID)

subtarget:
        echo $$PPID