and -or

https://stackoverflow.com/questions/5584872/complex-conditions-check-in-makefile

https://stackoverflow.com/questions/4036191/sources-from-subdirectories-in-makefile

cheat-sheet

https://devhints.io/makefile

check_executables

# detect what shell is used
ifeq ($(findstring cmd.exe,$(SHELL)),cmd.exe)
$(info "shell Windows cmd.exe")
DEVNUL := NUL
WHICH := where
else
$(info "shell Bash")
DEVNUL := /dev/null
WHICH := which
endif

# detect platform independently if gcc is installed
ifeq ($(shell ${WHICH} gcc 2>${DEVNUL}),)
$(error "gcc is not in your system PATH")
else
$(info "gcc found")
endif


## optionally when I need to detect more tools I can use:

EXECUTABLES = ls dd 
K := $(foreach myTestCommand,$(EXECUTABLES),\
        $(if $(shell ${WHICH} $(myTestCommand) 2>${DEVNUL} ),\
            $(myTestCommand) found,\
            $(error "No $(myTestCommand) in PATH)))
$(info ${K})        

cross-compile-ipfs-mipsle

# https://ftp-master.debian.org/keys.html
curl -fsSL https://ftp-master.debian.org/keys/archive-key-10.asc | sudo apt-key add - && echo "deb http://ftp.ca.debian.org/debian buster main" | sudo tee /etc/apt/sources.list.d/debian-buster.list

sudo apt install libssl-dev
sudo apt install gccgo-mipsel-linux-gnu
sudo dpkg --add-architecture i386 && sudo apt update
sudo dpkg --add-architecture mipsel && sudo apt update
sudo dpkg --add-architecture amd64 && sudo apt update

sudo apt install libssl-dev:i386 libssl-dev:mipsel


GO111MODULE=on CC=mipsel-linux-gnu-gccgo CGO_ENABLED=1 make build GOFLAGS=-tags=openssl GOOS=linux GOARCH=mipsle

dynamically choose os commands

https://stackoverflow.com/questions/39272954/how-to-prompt-user-for-y-n-in-my-makefile-with-pure-make-syntaxis

recursive wildcard search

# Make does not offer a recursive wildcard function, so here's one:
rwildcard=$(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))

# How to recursively find all files with the same name in a given folder
ALL_INDEX_HTMLS := $(call rwildcard,foo/,index.html)

# How to recursively find all files that match a pattern
ALL_HTMLS := $(call rwildcard,foo/,*.html)

Windows _linux translator

https://stackoverflow.com/questions/44339327/copy-file-in-windows-makefile