If statement in makefile

Question

I found that I can use ifneq in makefile and I tried to compare 0 and the output of command stat:

@for f in `find $(PATH_PAGES) -name *.hbs`; do \
    ifneq "`stat -c '%Y' $$f`" "0";
        //some code here
    endif
done

But in terminal I've got an error: ifneq: command not found

Is there a different way to compare this or maybe I'm doing something wrong?

`-c` is not a portable option to stat, so I'm guessing that you are using it to determine if the file has been modified. `make` is pretty good at comparing timestamps to determine if a dependency is out of date, and it would probably be better to let `make` evaluate the timestamps. Also, you will need line continuations (and probably more semi-colons), since make will treat multiple lines as multiple commands. — William Pursell, Jul 11 '13 at 13:51
So, how can I let `make` determine timestamps? There is a command in that loop and `make` always call this command on each file, even if this file hasn't been modified. So in that loop I use `touch` to change timestamp and now I want to compare time after timestamp that I use `touch --date="1970-01-01 03:00" $$f;` and 0. I know It's awful solution but I need to edit that makefile and this is my first day with all that makes and makefiles) — Ivan Shcherbakov, Jul 11 '13 at 14:00

legoscia · Accepted Answer · 2013-07-11T14:04:03.670

4

In this case you don't want to use Make's ifneq, because it does text substitution before handing over the command to the shell, but you have a shell loop that needs to do different things in each iteration depending on the output of a shell command.

Use the shell if instead:

if [ "`stat -c '%Y' $$f`" != "0" ]; then
    //some code here
fi

edited Jul 11 '13 at 14:04

answered Jul 11 '13 at 13:32

legoscia

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Thanks! By the way I added "then" after if condition, and it now works. – Ivan Shcherbakov Jul 11 '13 at 13:53
@IvanShcherbakov, right, I forgot that. I edited the answer :) – legoscia Jul 11 '13 at 14:04

score 3 · Answer 2 · edited May 23 '17 at 10:34

3

If you want to use makefile's if condition then there should not be [TAB] before the if statement because if you specify [TAB] then it is treated as shell command thats why you are getting error that ifneq:command not found its not there in shell.

May be this Conditionals in Makefile: missing separator error? can help in getting better understanding with makefiles

edited May 23 '17 at 10:34

Community

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answered Jul 12 '13 at 04:32

Sagar Sakre

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score 0 · Answer 3 · answered May 27 '20 at 18:24

0

I found that I needed to prepend the if with a @, and backslashes proved to be necessary as well -

@if [ "`stat -c '%Y' $$f`" != "0" ]; then\
    echo hello world;\
fi

answered May 27 '20 at 18:24

skwidbreth

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If statement in makefile

3 Answers3