Change snapper configuration location via Makefile

Update installation instructions.

Fixes #43.

Makefile

@@ -17,6 +17,7 @@
 
 PKGNAME = snap-sync
 PREFIX ?= /usr
+SNAPPER_CONFIG ?= /etc/sysconfig/snapper
 
 BIN_DIR = $(DESTDIR)$(PREFIX)/bin
 SYSTEMD_DIR = $(DESTDIR)$(PREFIX)/lib/systemd/system
@@ -24,5 +25,6 @@ SYSTEMD_DIR = $(DESTDIR)$(PREFIX)/lib/systemd/system
 .PHONY: install
 
 install:
+	sed -i 's@^SNAPPER_CONFIG.*@SNAPPER_CONFIG='$(SNAPPER_CONFIG)'@g' bin/$(PKGNAME)
 	@install -Dm755 bin/* -t $(BIN_DIR)/
 	@install -Dm644 systemd/* -t $(SYSTEMD_DIR)/

README.md

@@ -20,6 +20,25 @@ have to be sent.
 
 snapper is required.
 
+## Installation
+
+Run:
+
+    # make install
+
+By default it will look for the snapper configuration file at
+`/etc/sysconfig/snapper`. To change this pass `SNAPPER_CONFIG` to make
+with the location of the configuration file. For example, with Ubuntu
+you will want to install:
+
+    # make SNAPPER_CONFIG=/etc/default/snapper install
+
+For Arch Linux it would be:
+
+    # make SNAPPER_CONFIG=/etc/conf.d/snapper install
+
+The package is available in the [AUR](https://aur.archlinux.org/packages/snap-sync/).
+
 ## Options
 
     Usage: snap-sync [options]

bin/snap-sync

@@ -12,6 +12,8 @@ set -o errtrace
 version="0.4"
 name="snap-sync"
 
+SNAPPER_CONFIG=/etc/sysconfig/snapper
+
 TMPDIR=$(mktemp -d)
 PIPE=$TMPDIR/$name.out
 mkfifo $PIPE