function cd_history () {
    local old
    local p
    local b
    if [ -z "$1" ]
    then \cd "$HOME"
         return
    fi
    old=$( tail -n 149 "$HOME/.bash_cdhistory" )
    echo "$old" > "$HOME/.bash_cdhistory"
    \cd "$1"
    p=$( pwd )
    b=$( basename "$p" )
    echo $b":"$p >> "$HOME/.bash_cdhistory"
}
alias cd=cd_history

function qcd() {
    local OPTIND
    local OPTARG
    local opt
    
    while getopts aLl:hm opt
    do  case "$opt" in
        a)
            # Adding
            local name=${!OPTIND}
            if [ -z "$name" ]
            then name=$( basename $( pwd ))
            fi

            echo "$name":$( pwd )
            echo "$name":$( pwd ) >> ~/.qcd
            return
        ;;
        L)
            echo ==History ~/.bash_cdhistory:
            cat ~/.bash_cdhistory
            echo 
            echo ==Saved ~/.qcd:
            cat ~/.qcd
            return
        ;;
        l)
            local d=$( grep -h ^"$OPTARG" ~/.qcd <( tac ~/.bash_cdhistory ) | head -n 1 )
            d=${d/*:/}
            echo $d
            return
        ;;
        m)
            local IFS=$'\n'
            for line in $( cat ~/.bash_cdhistory );
            do if [ -d "${line/*:/}" ];
               then echo "$line" >> ~/.bash_cdhistory.tmp
               fi
            done
            mv ~/.bash_cdhistory.tmp ~/.bash_cdhistory
            for line in $( cat ~/.qcd );
            do if [ -d "${line/*:/}" ];
               then echo "$line" >> ~/.qcd.tmp
               fi
            done
            mv ~/.qcd.tmp ~/.qcd
            return
        ;;
        h)
            echo 'qcd [-mLh]|[-al] [name]
Change current working path based on the list ~/.qcd
Keeps a history of folders visited in ~/.bash_cdhistory

 -a [name]   Adds the path to the list
  You may add the name of the path, but when omitted
  the basename will be used

 -l [name]   Show the match, but do not change
 -L          Lists the paths
 -m          Maintain the list, deleting non-existing entries'
           return
        ;;
        esac
    done
    unset OPTSTRING
    unset OPTIND
    if [ -z "$1" ]
    then \cd
    else
     d=$( grep -h ^"$1" ~/.qcd <( tac ~/.bash_cdhistory ) | head -n 1 )
     d=${d/*:/}
     if [ ! -z "$d" ]
     then \cd "$d" 
     fi
    fi
}


function whenfilechanges() {
    [ -z "$1" ] && { echo 'Usage: whenfilechanges "file" "some" "command" 
      Follows the modification time of the "file" and runs the command 
      at every change.  '
        return
    }
    [ -e "$1" ] || { echo $1 not found
        return
    }
    local fname
    local otime
    local ntime
    
    fname=$1
    shift 1
    otime=$( stat -c %Z "$fname" )
    while : 
    do ntime=$( stat -c %Z "$fname" )
        [ "$ntime" -ne "$otime" ] && {
            eval "$@"
            otime=$( stat -c %Z "$fname" )
        }
        
       sleep 2
    done

}