Multiple bash hooks upon changing directories (set env var, switch node version, switch history file)

.sharedhistory.sh

shopt -s histappend
PROMPT_COMMAND="history -a;history -c;history -r;$PROMPT_COMMAND"

SHARED_HISTORY_DIR="$HOME/.sharedhistory"
mkdir -p $SHARED_HISTORY_DIR

function __sharedhistory_chpwd() {
    if [[ -n $PROJECT ]]; then
        local pwd_escaped=$(echo $PWD | sed 's/[\/ ]/~/g')
        HISTFILE="$SHARED_HISTORY_DIR/$PROJECT"
    else
        HISTFILE="$HOME/.bash_history"
    fi
    if [[ ! -f $HISTFILE ]]; then
        touch $HISTFILE;
    fi
    chmod 660 $HISTFILE;
    export HISTFILE
}


#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

# first time
__sharedhistory_chpwd



# add shared history functionality
[[ " ${chpwd_functions[*]} " == *" __sharedhistory_chpwd "* ]] ||
  chpwd_functions+=(__sharedhistory_chpwd)

export chpwd_functions;

avn.sh

##
# Functionality specific to avn
#
# This is slightly modified from the script in https://github.com/wbyoung/avn ;
# Specifically I stole the idea of hooks and made it general

if [[ -n "${BASH_VERSION:-}" ]]; then
  true
elif [[ -n "${ZSH_VERSION:-}" ]]; then
  setopt null_glob
else
  printf "%b" "avn does not yet support this shell\n"
fi

export PATH="$HOME/.avn/bin:$PATH"

# plugins may add to this, it's an array of version file names
export -a __avn_files
__avn_files=(".node-version")

# the full path to the active version file, /path/to/.node-version
export __avn_active_file

# load each plugin
for plugin in $HOME/.avn/plugins/*
do
  [[ -f "$plugin/load.sh" ]] && . "$plugin/load.sh"
done

# run _avn & eval results written to fd 3
function __avn_eval() {
  typeset cmd actions actions_result options

  cmd=$1
  shift

  [[ -t 1 ]] && options="--color"

  actions=$(_avn ${cmd} $options "$@" 3>&1 1>&2)
  actions_result=$?
  if [[ $actions_result -eq 0 ]]
  then
    eval "$actions"
  fi
}

# avn chpwd hook
function __avn_chpwd() {
  local file=$(__avn_find_file)
  local dir=${file%/*}
  local name=${file##*/}

  [[ -n "$file" ]] && [[ "$file" != "$__avn_active_file" ]] &&
    __avn_eval chpwd "$dir" "$name" || true

  __avn_active_file=$file

  true
}

# debug that includes file lookup
function __avn_debug() {
  local file=$(__avn_find_file)
  local dir=${file%/*}
  local name=${file##*/}

  _avn explain -v "$dir" "$name"
}

# find version specification file
function __avn_find_file() {
  local found
  local dir=$PWD
  while [[ -z "$found" ]] && [[ "$dir" != "" ]]; do
    for file in "${__avn_files[@]}"; do
      if [[ -f "$dir/$file" ]]; then
        found="$dir/$file"
        break
      fi
    done
    if [[ "$dir" == "$HOME" ]]; then
      break
    fi
    dir=${dir%/*}
  done
  echo $found
}

__avn_chpwd # run chpwd once since the shell was just loaded


##
# Hooks that will happen after the working directory is changed
#

# add avn functionality
[[ " ${chpwd_functions[*]} " == *" __avn_chpwd "* ]] ||
  chpwd_functions+=(__avn_chpwd)

export chpwd_functions;

projects.sh

# shortcut for projects directory
[ -e "$HOME/p" ] && export PROJECTS="$HOME/p"

function __projects_chpwd() {
  PROJECT=""
  if [[ $PWD =~ ^$PROJECTS ]]; then
    if [[ $PWD =~ ^$PROJECTS/([^/]+) ]]; then
        PROJECT="${BASH_REMATCH[1]}"
    fi
  fi
  export PROJECT
}

# add projects detection functionality
[[ " ${chpwd_functions[*]} " == *" __projects_chpwd "* ]] ||
  chpwd_functions+=(__projects_chpwd)

__projects_chpwd


# switch node versions upon entering dir with .nvmrc. uses chpwd_functions.
[[ -s "$HOME/avn.sh" ]] && source "$HOME/avn.sh"

# switch history file upon entering a new $PROJECTS/* folder. uses chpwd_functions
[[ -s "$HOME/.sharedhistory.sh" ]] && source "$HOME/.sharedhistory.sh"