Fix ps command flags for FreeBSD

This was reported by @duck in #45

CHANGELOG.md

@@ -7,6 +7,8 @@
 - save command strategy: 'gdb'
 - rename default strategy name to 'ps'
 - create `expect` script that can fully restore tmux environment
+- fix default save command strategy `ps` command flags. Flags are different for
+  FreeBSD.
 
 ### v1.3.0, 2014-09-20
 - remove dependency on `pgrep` command. Use `ps` for fetching process names.

save_command_strategies/ps.sh

@@ -10,8 +10,15 @@ exit_safely_if_empty_ppid() {
 	fi
 }
 
+ps_command_flags() {
+	case $(uname -s) in
+		FreeBSD) echo "-ao" ;;
+		*) echo "-eo" ;;
+	esac
+}
+
 full_command() {
-	ps -eo "ppid command" |
+	ps "$(ps_command_flags)" "ppid command" |
 		sed "s/^ *//" |
 		grep "^${PANE_PID}" |
 		cut -d' ' -f2-