2010年7月10日 · From Managing Projects with GNU Make, 3rd Edition, p. 16 (it's under GNU Free Documentation License): Automatic variables are set by make after a rule is matched. They provide access to elements from the target and prerequisite lists so you don’t have to explicitly specify any filenames.

2019年1月6日 · = called recursive expanded variable or lazy expanded variable. in below example, when make read this line. VAR1 = $(VAR1) + 100 make just stored value from righthand side VAR1 into lefthand side VAR1 without expanding. When make tried to read $(VAR1) which is defined on left hand side. this is keep repeating and result into infinite loop

2009年8月2日 · -> ls -l $(which gmake make) lrwxrwxrwx 1 root root 4 Jun 5 2007 /usr/bin/gmake -> make -rwxr-xr-x 1 root root 168976 Jul 13 2006 /usr/bin/make gmake stands for GNU make. There're different implementations of make. On Linux machine most probably make will by GNU and to make user's life isier make is soft linked to gmake.

Then GNU cloned it. Then GNU enhanced it _extensively, so much so that they had to abandon backward compatibility. The GNU version is so much better that very few use the original Unix version any more and it has largely disappeared. Many Linux systems contain both the original Make (called 'make') and the GNU version Make (called 'gmake').

2011年12月22日 · The trick here is that you've got an obscure combination of two different syntaxes. The make(1) syntax is the use of an action starting with @, which is simply not to echo the command. So a rule like . always: @echo this always happens won't emit

+ means 'execute this command under make -n' (or 'make -t' or 'make -q') when commands are not normally executed. See also the POSIX specification for make and also §9.3 of the GNU Make manual. The + notation is a (POSIX-standardized) generalization of the de facto (non-standardized) mechanism whereby a command line containing ${MAKE} or ...

2016年8月16日 · Each line of a make recipe is handed to the shell independently. Thus, if you want to execute something in the directory /root then the recipe should be something like cd /root/ && $(MAKE) all. As written, the line cd /root/ will cd into /root and exit. Then $(MAKE) all is executed in the current directory not /root/. This is covered in GNU ...

Let me refer to GNU Make manual "Setting variables" and "Flavors", and add some comments. Recursively expanded variables. The value you specify is installed verbatim; if it contains references to other variables, these references are expanded whenever this variable is substituted (in the course of expanding some other string).

2011年7月22日 · Important note: when you define a function that calls $(MAKE), you must add the @+ after the equality sign. So like: sub_make = @+$(MAKE) -C $(TOPDIR)/subdir/$(1) $(2). Otherwise make won't pass descriptors and options it ought to to submake calls, which would manifest itself as a warning: jobserver unavailable: using -j1. Add '+' to parent ...

For GNU make >= 3.81, which was introduced in 2006. ROOT_DIR := $(dir $(realpath $(lastword $(MAKEFILE_LIST)))) MAKEFILE_LIST changes as include files come in and out of scope. The last item is the current file. lastword plucks the last item (Makefile name, relative to pwd)