Create new file only if there are changes

Code submitted by @vburdo in
https://github.com/tmux-plugins/tmux-resurrect/issues/156

CHANGELOG.md

@@ -18,6 +18,7 @@
 - `mutt` added to the list of automatically restored programs
 - added guide for migrating from tmuxinator
 - fixed a bug for restoring commands on tmux 2.5 (and probably tmux 2.4)
+- do not create another resurrect file if there are no changes (credit @vburdo)
 
 ### v2.4.0, 2015-02-23
 - add "tmux-test"

scripts/helpers.sh

@@ -56,6 +56,10 @@ capture_pane_contents_option_on() {
 	[ "$option" == "on" ]
 }
 
+files_differ() {
+	! cmp -s "$1" "$2"
+}
+
 save_bash_history_option_on() {
 	local option="$(get_tmux_option "$bash_history_option" "off")"
 	[ "$option" == "on" ]

scripts/save.sh

@@ -254,12 +254,17 @@ dump_bash_history() {
 
 save_all() {
 	local resurrect_file_path="$(resurrect_file_path)"
+	local last_resurrect_file="$(last_resurrect_file)"
 	mkdir -p "$(resurrect_dir)"
 	fetch_and_dump_grouped_sessions > "$resurrect_file_path"
 	dump_panes   >> "$resurrect_file_path"
 	dump_windows >> "$resurrect_file_path"
 	dump_state   >> "$resurrect_file_path"
-	ln -fs "$(basename "$resurrect_file_path")" "$(last_resurrect_file)"
+	if files_differ "$resurrect_file_path" "$last_resurrect_file"; then
+		ln -fs "$(basename "$resurrect_file_path")" "$last_resurrect_file"
+	else
+		rm "$resurrect_file_path"
+	fi
 	if capture_pane_contents_option_on; then
 		mkdir -p "$(pane_contents_dir)"
 		dump_pane_contents