How to run m4 inline

Question

I have the following to process a file:

$ vim file2
define(add2, `eval($1+$2)')
Adding 2+4=add2(2,4)

And to run:

$ m4 file
Adding 2+4=6

Is there a way to run m4 with the file contents inline? For example something like:

$ m4 <inline>
define(add2, `eval($1+$2)')
Adding 2+4=add2(2,4)
<ctrl-d>
# Adding 2+4=6

How could that be done?

Answer 1

One option is to the 'interactive mode':

  -e, --interactive
     unbuffer output, ignore interrupts

In which case you can do:

IM-MM:DD_Objects david$ m4 -e
define(add2, `eval($1+$2)')
Adding 2+4=add2(2,4)

Adding 2+4=6