directory based history bash profile

mycd.sh

function mycd()
{
    #if this directory is writable then write to directory-based history file
    #otherwise write history in the usual home-based history file                    
    tmpDir=$PWD
    echo "#"`date '+%s'` >> $HISTFILE
    echo $USER' has exited '$PWD' for '$@ >> $HISTFILE
    builtin cd "$@" # do actual cd
    if [ -w $PWD ]; then export HISTFILE="$PWD/.dir_bash_history"; touch $HISTFILE; chmod --silent 777 $HISTFILE;
    else export HISTFILE="$HOME/.bash_history";
    fi
    echo "#"`date '+%s'` >> $HISTFILE
    echo $USER' has entered '$PWD' from '$OLDPWD >> $HISTFILE

}
alias cd="mycd"
#initial shell opened                                                                                     
export HISTFILE="$PWD/.dir_bash_history"
#timestamp all history entries                                                                            
export HISTTIMEFORMAT="%h/%d - %H:%M:%S "
export HISTCONTROL=ignoredups:erasedups
export HISTSIZE=1000000
export HISTFILESIZE=1000000
shopt -s histappend ## append, no clearouts                                                               
shopt -s histverify ## edit a recalled history line before executing                                      
shopt -s histreedit ## reedit a history substitution line if it failed                                    

## Save the history after each command finishes                                                           
## (and keep any existing PROMPT_COMMAND settings)                                                        
export PROMPT_COMMAND="history -a; history -c; history -r; $PROMPT_COMMAND"