Fix wording of install-nbextension command help

Thanks to @takluyver for the review comment.

IPython/html/nbextensions.py

@@ -1,351 +1,351 b''
 # coding: utf-8
 """Utilities for installing Javascript extensions for the notebook"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import print_function
 
 import os
 import shutil
 import sys
 import tarfile
 import zipfile
 import uuid
 from os.path import basename, join as pjoin
 
 # Deferred imports
 try:
     from urllib.parse import urlparse  # Py3
     from urllib.request import urlretrieve
 except ImportError:
     from urlparse import urlparse
     from urllib import urlretrieve
 
 from IPython.utils.path import get_ipython_dir, ensure_dir_exists
 from IPython.utils.py3compat import string_types, cast_unicode_py2
 from IPython.utils.tempdir import TemporaryDirectory
 
 class ArgumentConflict(ValueError):
     pass
 
 # Packagers: modify the next block if you store system-installed nbextensions elsewhere (unlikely)
 SYSTEM_NBEXTENSIONS_DIRS = []
 
 if os.name == 'nt':
     programdata = os.environ.get('PROGRAMDATA', None)
     if programdata: # PROGRAMDATA is not defined by default on XP.
         SYSTEM_NBEXTENSIONS_DIRS = [pjoin(programdata, 'jupyter', 'nbextensions')]
     prefixes = []
 else:
     prefixes = [os.path.sep + pjoin('usr', 'local'), os.path.sep + 'usr']
 
 # add sys.prefix at the front
 if sys.prefix not in prefixes:
     prefixes.insert(0, sys.prefix)
 
 for prefix in prefixes:
     nbext = pjoin(prefix, 'share', 'jupyter', 'nbextensions')
     if nbext not in SYSTEM_NBEXTENSIONS_DIRS:
         SYSTEM_NBEXTENSIONS_DIRS.append(nbext)
 
 if os.name == 'nt':
     # PROGRAMDATA
     SYSTEM_NBEXTENSIONS_INSTALL_DIR = SYSTEM_NBEXTENSIONS_DIRS[-1]
 else:
     # /usr/local
     SYSTEM_NBEXTENSIONS_INSTALL_DIR = SYSTEM_NBEXTENSIONS_DIRS[-2]
 
 
 def _should_copy(src, dest, verbose=1):
     """should a file be copied?"""
     if not os.path.exists(dest):
         return True
     if os.stat(src).st_mtime - os.stat(dest).st_mtime > 1e-6:
         # we add a fudge factor to work around a bug in python 2.x
         # that was fixed in python 3.x: http://bugs.python.org/issue12904
         if verbose >= 2:
             print("%s is out of date" % dest)
         return True
     if verbose >= 2:
         print("%s is up to date" % dest)
     return False
 
 
 def _maybe_copy(src, dest, verbose=1):
     """copy a file if it needs updating"""
     if _should_copy(src, dest, verbose):
         if verbose >= 1:
             print("copying %s -> %s" % (src, dest))
         shutil.copy2(src, dest)
 
 def _safe_is_tarfile(path):
     """safe version of is_tarfile, return False on IOError"""
     try:
         return tarfile.is_tarfile(path)
     except IOError:
         return False
 
 
 def _get_nbext_dir(nbextensions_dir=None, user=False, prefix=None):
     """Return the nbextension directory specified"""
     if sum(map(bool, [user, prefix, nbextensions_dir])) > 1:
         raise ArgumentConflict("Cannot specify more than one of user, prefix, or nbextensions_dir.")
     if user:
         nbext = pjoin(get_ipython_dir(), u'nbextensions')
     else:
         if prefix:
             nbext = pjoin(prefix, 'share', 'jupyter', 'nbextensions')
         elif nbextensions_dir:
             nbext = nbextensions_dir
         else:
             nbext = SYSTEM_NBEXTENSIONS_INSTALL_DIR
     return nbext
 
 
 def check_nbextension(files, user=False, prefix=None, nbextensions_dir=None):
     """Check whether nbextension files have been installed
     
     Returns True if all files are found, False if any are missing.
 
     Parameters
     ----------
 
     files : list(paths)
         a list of relative paths within nbextensions.
     user : bool [default: False]
         Whether to check the user's .ipython/nbextensions directory.
         Otherwise check a system-wide install (e.g. /usr/local/share/jupyter/nbextensions).
     prefix : str [optional]
         Specify install prefix, if it should differ from default (e.g. /usr/local).
         Will check prefix/share/jupyter/nbextensions
     nbextensions_dir : str [optional]
         Specify absolute path of nbextensions directory explicitly.
     """
     nbext = _get_nbext_dir(nbextensions_dir, user, prefix)
     # make sure nbextensions dir exists
     if not os.path.exists(nbext):
         return False
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     return all(os.path.exists(pjoin(nbext, f)) for f in files)
 
 
 def install_nbextension(path, overwrite=False, symlink=False, user=False, prefix=None, nbextensions_dir=None, destination=None, verbose=1):
     """Install a Javascript extension for the notebook
     
     Stages files and/or directories into the nbextensions directory.
     By default, this compares modification time, and only stages files that need updating.
     If `overwrite` is specified, matching files are purged before proceeding.
     
     Parameters
     ----------
     
     path : path to file, directory, zip or tarball archive, or URL to install
         By default, the file will be installed with its base name, so '/path/to/foo'
         will install to 'nbextensions/foo'. See the destination argument below to change this.
         Archives (zip or tarballs) will be extracted into the nbextensions directory.
     overwrite : bool [default: False]
         If True, always install the files, regardless of what may already be installed.
     symlink : bool [default: False]
         If True, create a symlink in nbextensions, rather than copying files.
         Not allowed with URLs or archives. Windows support for symlinks requires
         Vista or above, Python 3, and a permission bit which only admin users
         have by default, so don't rely on it.
     user : bool [default: False]
         Whether to install to the user's .ipython/nbextensions directory.
         Otherwise do a system-wide install (e.g. /usr/local/share/jupyter/nbextensions).
     prefix : str [optional]
         Specify install prefix, if it should differ from default (e.g. /usr/local).
         Will install to prefix/share/jupyter/nbextensions
     nbextensions_dir : str [optional]
         Specify absolute path of nbextensions directory explicitly.
     destination : str [optional]
         name the nbextension is installed to.  For example, if destination is 'foo', then
         the source file will be installed to 'nbextensions/foo', regardless of the source name.
         This cannot be specified if an archive is given as the source.
     verbose : int [default: 1]
         Set verbosity level. The default is 1, where file actions are printed.
         set verbose=2 for more output, or verbose=0 for silence.
     """
     nbext = _get_nbext_dir(nbextensions_dir, user, prefix)
     # make sure nbextensions dir exists
     ensure_dir_exists(nbext)
     
     if isinstance(path, (list, tuple)):
         raise TypeError("path must be a string pointing to a single extension to install; call this function multiple times to install multiple extensions")
     
     path = cast_unicode_py2(path)
 
     if path.startswith(('https://', 'http://')):
         if symlink:
             raise ValueError("Cannot symlink from URLs")
         # Given a URL, download it
         with TemporaryDirectory() as td:
             filename = urlparse(path).path.split('/')[-1]
             local_path = os.path.join(td, filename)
             if verbose >= 1:
                 print("downloading %s to %s" % (path, local_path))
             urlretrieve(path, local_path)
             # now install from the local copy
             install_nbextension(local_path, overwrite=overwrite, symlink=symlink, nbextensions_dir=nbext, destination=destination, verbose=verbose)
     elif path.endswith('.zip') or _safe_is_tarfile(path):
         if symlink:
             raise ValueError("Cannot symlink from archives")
         if destination:
             raise ValueError("Cannot give destination for archives")
         if verbose >= 1:
             print("extracting %s to %s" % (path, nbext))
 
         if path.endswith('.zip'):
             archive = zipfile.ZipFile(path)
         elif _safe_is_tarfile(path):
             archive = tarfile.open(path)
         else:
             raise ValueError("Could not extract archive")
         archive.extractall(nbext)
         archive.close()
     else:
         if not destination:
             destination = basename(path)
         full_dest = pjoin(nbext, destination)
         if overwrite and os.path.exists(full_dest):
             if verbose >= 1:
                 print("removing %s" % full_dest)
             if os.path.isdir(full_dest) and not os.path.islink(full_dest):
                 shutil.rmtree(full_dest)
             else:
                 os.remove(full_dest)
 
         if symlink:
             path = os.path.abspath(path)
             if not os.path.exists(full_dest):
                 if verbose >= 1:
                     print("symlink %s -> %s" % (full_dest, path))
                 os.symlink(path, full_dest)
         elif os.path.isdir(path):
             path = pjoin(os.path.abspath(path), '') # end in path separator
             for parent, dirs, files in os.walk(path):
                 dest_dir = pjoin(full_dest, parent[len(path):])
                 if not os.path.exists(dest_dir):
                     if verbose >= 2:
                         print("making directory %s" % dest_dir)
                     os.makedirs(dest_dir)
                 for file in files:
                     src = pjoin(parent, file)
                     # print("%r, %r" % (dest_dir, file))
                     dest_file = pjoin(dest_dir, file)
                     _maybe_copy(src, dest_file, verbose)
         else:
             src = path
             _maybe_copy(src, full_dest, verbose)
 
 #----------------------------------------------------------------------
 # install nbextension app
 #----------------------------------------------------------------------
 
 from IPython.utils.traitlets import Bool, Enum, Unicode, TraitError
 from IPython.core.application import BaseIPythonApplication
 
 flags = {
     "overwrite" : ({
         "NBExtensionApp" : {
             "overwrite" : True,
         }}, "Force overwrite of existing files"
     ),
     "debug" : ({
         "NBExtensionApp" : {
             "verbose" : 2,
         }}, "Extra output"
     ),
     "quiet" : ({
         "NBExtensionApp" : {
             "verbose" : 0,
         }}, "Minimal output"
     ),
     "symlink" : ({
         "NBExtensionApp" : {
             "symlink" : True,
         }}, "Create symlink instead of copying files"
     ),
     "user" : ({
         "NBExtensionApp" : {
             "user" : True,
         }}, "Install to the user's IPython directory"
     ),
 }
 flags['s'] = flags['symlink']
 
 aliases = {
     "ipython-dir" : "NBExtensionApp.ipython_dir",
     "prefix" : "NBExtensionApp.prefix",
     "nbextensions" : "NBExtensionApp.nbextensions_dir",
     "destination" : "NBExtensionApp.destination",
 }
 
 class NBExtensionApp(BaseIPythonApplication):
     """Entry point for installing notebook extensions"""
     
     description = """Install IPython notebook extensions
     
     Usage
     
-        ipython install-nbextension [file, folder, archive, or url]
+        ipython install-nbextension path/url
     
-    This copies a file and/or a folder into the IPython nbextensions directory.
+    This copies a file or a folder into the IPython nbextensions directory.
     If a URL is given, it will be downloaded.
     If an archive is given, it will be extracted into nbextensions.
     If the requested files are already up to date, no action is taken
     unless --overwrite is specified.
     """
     
     examples = """
     ipython install-nbextension /path/to/myextension
     """
     aliases = aliases
     flags = flags
     
     overwrite = Bool(False, config=True, help="Force overwrite of existing files")
     symlink = Bool(False, config=True, help="Create symlinks instead of copying files")
     user = Bool(False, config=True, help="Whether to do a user install")
     prefix = Unicode('', config=True, help="Installation prefix")
     nbextensions_dir = Unicode('', config=True, help="Full path to nbextensions dir (probably use prefix or user)")
     destination = Unicode('', config=True, help="Destination for the copy or symlink")
     verbose = Enum((0,1,2), default_value=1, config=True,
         help="Verbosity level"
     )
     
     def install_extensions(self):
         if len(self.extra_args)>1:
             raise ValueError("only one nbextension allowed at a time.  Call multiple times to install multiple extensions.")
         install_nbextension(self.extra_args[0],
             overwrite=self.overwrite,
             symlink=self.symlink,
             verbose=self.verbose,
             user=self.user,
             prefix=self.prefix,
             destination=self.destination,
             nbextensions_dir=self.nbextensions_dir,
         )
     
     def start(self):
         if not self.extra_args:
             for nbext in [pjoin(self.ipython_dir, u'nbextensions')] + SYSTEM_NBEXTENSIONS_DIRS:
                 if os.path.exists(nbext):
                     print("Notebook extensions in %s:" % nbext)
                     for ext in os.listdir(nbext):
                         print(u"    %s" % ext)
         else:
             try:
                 self.install_extensions()
             except ArgumentConflict as e:
                 print(str(e), file=sys.stderr)
                 self.exit(1)
 
 
 if __name__ == '__main__':
     NBExtensionApp.launch_instance()