On Wed, Jan 19, 2022 at 11:19 PM Paul Smith <psm...@gnu.org> wrote: > > On Wed, 2022-01-19 at 19:47 +0800, Hongyi Zhao wrote: > > This reminds me of the following similar problems when using GNU > > Makefile variable assignment as discussed here [1]: > > I recommend that people read the GNU make manual, rather than websites: > > https://www.gnu.org/software/make/manual/html_node/Using-Variables.html > > > VAL = foo > > VARIABLE = $(VAL) > > > > In the above usage, can I also change to the following? > > > > VAL = foo > > VARIABLE = $$VAL > > I don't quite understand the question. Of course you CAN do that. If > your question is, does it mean the same thing then no, it does not. > > The first one sets the value of the variable VARIABLE to the string > $(VAL) and the second one sets the value of the variable VARIABLE to > the string $$VAL. > > These are definitely not the same: when $(VARIABLE) is expanded after > the first one, the expansion will be "foo" (without quotes). When > $(VARIABLE) is expanded after the second one, the expansion will be the > literal string "$VAL" (without quotes). So they're not the same.
Maybe I didn't express my question clearly. I actually meant to say if the following one are equivalent to obtain the exit code: $($?) and $$? HZ
