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Re: -V, --verbose, as opposite of -s, --silent, --quiet

From: Alejandro Colomar (man-pages)
Subject: Re: -V, --verbose, as opposite of -s, --silent, --quiet
Date: Mon, 25 Oct 2021 22:28:44 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0

Hello Paul, Dmitry, and David!

> On Sat, Oct 23, 2021 at 6:06 AM Paul Smith <psmith@gnu.org
> <mailto:psmith@gnu.org>> wrote:
> On Sat, 2021-10-23 at 03:01 +0200, Alejandro Colomar (man-pages) wrote:
>      > I'd like a project to use '--silent' by default, to have readable
>      > output, and hide most of the full commands, which would be too
>      > noisy.
>      >
>      > So, ideally, I'd like to have 'MAKEFLAGS += --silent' in the
>      > Makefile.
>     Actually what you really want is the .SILENT special target.
> https://www.gnu.org/software/make/manual/html_node/Special-Targets.html#index-_002eSILENT > <https://www.gnu.org/software/make/manual/html_node/Special-Targets.html#index-_002eSILENT>
>     That leads to this best-practice way to handle verbose output:
>     http://make.mad-scientist.net/managing-recipe-echoing/
>     <http://make.mad-scientist.net/managing-recipe-echoing/>

Hmm! Yes, I knew about .SILENT, but didn't know about this usage of it. It's interesting and simple enough, so I've started using it.

Since I use '--warn-undefined-variables', and also to help readability to someone who may not know about this usage and may wonder what does that $(V) mean, I used the following:

V :=


On 10/23/21 10:28 PM, David Boyce wrote:
BTW we use a slightly different and, I think, slightly improved version of what's shown there (see below). Improvements are:

1. Either the verbose or the concise output is shown, vs both in verbose mode as the original does.

I thought about it, and I prefer printing both for the following reasons:

The verbose output tends to use many lines for each command, since it may easily use 500 characters per command. Having a short line that uses uppercase at the beginning makes it much easier to know where each command starts.

Also, if you put that into a log file, then you can easily grep for the short line that you know you want to search, and next to it will be the long line (something like a dictionary).

And anyway, one short line per command (typically around 5-8 lines) won't hurt readability too much.

2. It uses $(info ...) instead of echo which saves a fork/exec per recipe (note: this is safe only when used in the first recipe line).

Yup! I also use $(info ...) since mad scientist showed it to me. It made a huge impact in performance.

3. It provides a default "MAKING $@" message as demonstrated in the example.

Nah, I prefer explicit $(info ...) lines always. Makes it easier to read, and also I prefer showing the command that runs every target.



4. A special case is used to ensure the clean target is always verbose.


$ cat Makefile
.PHONY: all
all: hola

ifeq ($(V),)
   vb = $(info $(or $1,MAKING $(@F)))

hola: hola.o
         $(call vb)
         $(CC) -o $@ $(LDFLAGS) $^ $(LDLIBS)

%.o: %.c
         $(call vb,CC $(<F) -> $(@F))
         $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $<

.PHONY: clean
clean: clean_recipe = $(RM) *.o hola
         @$(info $(clean_recipe))

$ make clean; make
rm -f *.o hola
CC hola.c -> hola.o

$ make clean; make V=1
rm -f *.o hola
cc -c -o hola.o   hola.c
cc -o hola  hola.o

Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/

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