Makefile improvements

1. changed default goal just to show what 'make install' would do.

2. added "REVERSE" variable and "reverse-all" target to show/incorporate
back into the source the changes that have been made to installed
versions.

1 files changed, 37 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 691e8a9..5e70c84 100644
--- a/Makefile
+++ b/Makefile
@@ -2,16 +2,50 @@ ifndef HOME
 $(error "$$HOME" must be defined)
 endif
 
-DOTFILES := $(shell find dot \( -type f -o -type l \) -not -name '.*')
+.DEFAULT_GOAL = simulate-install
 
-DESTINATIONS = $(DOTFILES:dot/%=${HOME}/.%)
+SOURCES := $(shell find dot \( -type f -o -type l \) -not -name '.*')
+
+DESTINATIONS = $(SOURCES:dot/%=${HOME}/.%)
 
 ${HOME}/.gitconfig:
         ./src/gitconfig.sh
 
-EXECUTABLES = $(filter dot/local/bin/%, $(DOTFILES))
+EXECUTABLES = $(filter dot/local/bin/%, $(SOURCES))
 
+ifndef REVERSE
 $(HOME)/.%: dot/%
         install -D -m $(if $(filter $<, $(EXECUTABLES)), 0755, 0644) $< $@
+endif
+
+.PHONY: install simulate-install diff
+
+diff:
+        $(MAKE) REVERSE=y reverse-all | less -E
+
+help:
+        @echo 'To see all files changed outside the source tree:'
+        @echo
+        @echo '  make diff'
+        @echo
+        @echo 'To show the diff of one file (e.g. .xinitrc):'
+        @echo
+        @echo '  make REVERSE=y dot/xinitrc'
+        @echo
+        @echo 'To _copy_ from $$HOME/.xinitrc into the source tree:'
+        @echo
+        @echo '  make REVERSE=y WRITE_REVERSE=y dot/xinitrc'
+        @echo
+
+ifdef REVERSE
+.PHONY: reverse-all
+reverse-all: $(SOURCES)
+.FORCE:
+$(SOURCES): .FORCE
+        @diff -u3 $@ $(@:dot/%=$(HOME)/.%) || rsync $(if $(WRITE_REVERSE),,-n) -ui $(@:dot/%=$(HOME)/.%) $@
+endif
 
 install: $(DESTINATIONS)
+
+simulate-install:
+        $(MAKE) -n install