Add node_modules to PATH environment variable.

.local_profile.sh

# environment variables
bindir=$HOME/local/bin
if [[ ":$PATH:" != *":$bindir:"* ]]; then
    PATH=$bindir:$PATH
    export PATH
fi

# local development
export PROJECTS=$HOME/public

# virtualenv
export WORKON_HOME=$HOME/.venv
export PROJECT_HOME=$HOME/www
. /usr/local/bin/virtualenvwrapper.sh

# todo.txt-cli configuration
export TODOTXT_CFG_FILE=$HOME/.todo/todo.cfg
. $bindir/todo_completion
alias t="todo -d $TODOTXT_CFG_FILE"
complete -F _todo t
alias punch='/usr/bin/python $bindir/punch'

# aliases
sublime() {
    $bindir/sublime $@ &
}

# update bash path
pathup() {
    local action="$1"; shift
    case "$action" in
        popd)
            [[ $# -eq 0 ]] && builtin popd || builtin popd "$*" ;;
        cd|pushd)
            builtin $action "$*" ;;
        *)
            return ;;
    esac
    PATH=`/usr/bin/python $HOME/.path_env.py`
    export PATH
}
alias cd="pathup cd"
alias pushd="pathup pushd"
alias popd="pathup popd"

.path_env.py

#!/usr/bin/env python
# encoding: utf-8
import os
import sys


PROJECT_HOME = os.environ.get(
    'PROJECTS',
    os.path.join(os.environ.get('HOME'), 'public')
)


def back(path):
    """back(path) -- Get One level up in the tree from the path.

    -- path: a system path

    """
    return os.path.normpath(os.path.join(path, '..'))


def get_bin(path):
    """get_bin(path) -- Get the bin directory for the project.

    -- path: a project path

    """
    found = False
    bindir = ''
    while not found:
        bindir = os.path.join(path, 'node_modules', '.bin')
        found = os.path.exists(bindir) or path == PROJECT_HOME
        path = back(path)
    return bindir


def remove_project_from_path(path):
    """remove_project_from_path(path) -- Remove project from path directive.

    -- path: environment $PATH variable

    """
    return ':'.join([pathname for pathname in path.split(':') \
            if PROJECT_HOME not in pathname])


def add_project_to_path(project, path, sep=':'):
    """add_project_to_path(project, path, sep) -- Add project path to path
    directive.

    -- project: project pathname
    -- path: environment $PATH variable
    -- sep: separator used in $PATH variable

    """
    if project in path:
        return path
    return '{0}{1}{2}'.format(project, sep, path)



def normalize_path(path):
    """normalize_path(path) -- Normalize path by adding the current working
    directory and stripping led slash.

    -- path: variable passed by the shell script

    """
    if not path.startswith('/'):
        path = os.path.join(os.getcwd(), *path.split(os.path.sep))

    if path.endswith('/'):
        path = path[:-1]

    return path



def main(cwd=None):
    path = remove_project_from_path(os.environ.get('PATH'))

    if PROJECT_HOME not in cwd or cwd == PROJECT_HOME:
        return path

    bindir = get_bin(cwd)

    if not os.path.exists(bindir):
        return path

    return add_project_to_path(bindir, path)


if __name__ == '__main__':
    envpath = os.getcwd()
    sys.stdout.write(main(envpath))