help synopsis for 'tahoe ln' is confusing

[davidsarah]

tahoe ln --help just says:

tahoe ln FROM TO

followed by the global options help.

It should be clearer about the order of arguments (which are the same as Unix ln(1), i.e. TARGET then LINK_NAME).

[davidsarah]

CLI: improve synopsis and help description for 'tahoe ln' (now with test update and fix for typo). Also 'file' -> 'file or directory' in some of the 'tahoe --help' summaries. fixes #1230

[davidsarah]

$ bin/tahoe ln --help
tahoe ln FROM_LINK TO_LINK
Options:
  -q, --quiet             Operate silently.
  -V, --version           Display version numbers and exit.
      --version-and-path  Display version numbers and paths to their locations
                          and exit.
  -d, --node-directory=   Specify which Tahoe node directory should be used. The
                          directory should either contain a full Tahoe node, or
                          a file named node.url that points to some other Tahoe
                          node. It should also contain a file named
                          'private\aliases' which contains the mapping from
                          alias name to root dirnode URI. [default:
                          'D:\cygwin\home\David\.tahoe']
  -u, --node-url=         Specify the URL of the Tahoe gateway node, such as
                          'http://127.0.0.1:3456'. This overrides the URL found
                          in the --node-directory .
      --dir-cap=          Specify which dirnode URI should be used as the
                          'tahoe' alias.
      --help              Display this help and exit.

Use 'tahoe ln' to duplicate a link (directory entry) already on the grid to
elsewhere on the grid. For example 'tahoe ln alias:some_file alias:new_file'.
causes 'alias:new_file' to point to the same object that 'alias:some_file'
points to.

(The argument order is the same as Unix ln. To remember the order, you can think
of this command as copying a link, rather than copying a file as 'tahoe cp'
does. Then the argument order is consistent with that of 'tahoe cp'.)

If linking a remote file into a remote directory, you'll need to append a '/' to
the name of the remote directory, e.g., 'tahoe ln tahoe:file1 tahoe:dir/', not
'tahoe ln tahoe:file1 tahoe:dir'.

Note that it is not possible to use this command to create links between local
and remote files.

[warner]

patch looks fine. I can't apply it, however, because it accidentally depends upon a bunch of other patches, including one named "Eliminate direct dependencies of Tahoe-LAFS on pywin32".

I'll apply a normal diff instead.

[Brian Warner <warner@…>]

In b9fb74d2a09c43c7:

Improve 'tahoe ln' help text. Patch by David-Sarah. Closes #1230.

[warner]

Done. I took the liberty of expanding upon the 'ln file dir/' section.

[Brian Warner <warner@…>]

In [4980/ticket1306]:

Improve 'tahoe ln' help text. Patch by David-Sarah. Closes #1230.