+# ignore duplicate lines.
+HISTCONTROL=ignoredups
+# append to the history file.
+shopt -s histappend
+# automatically update window size if needed.
+shopt -s checkwinsize
+
+##############
+
+# make history writes immediate to avoid losing history if bash is zapped.
+echo $PROMPT_COMMAND | grep -q history
+if [ $? -ne 0 ]; then
+ # we only change the prompt command if we think it hasn't already been done.
+ export PROMPT_COMMAND="history -a;$PROMPT_COMMAND"
+fi