view mercurial/help/urls.txt @ 31956:c13ff31818b0

ui: add special-purpose atexit functionality

In spite of its longstanding use, Python's built-in atexit code is
not suitable for Mercurial's purposes, for several reasons:

* Handlers run after application code has finished.

* Because of this, the code that runs handlers swallows exceptions
  (since there's no possible stacktrace to associate errors with).
  If we're lucky, we'll get something spat out to stderr (if stderr
  still works), which of course isn't any use in a big deployment
  where it's important that exceptions get logged and aggregated.

* Mercurial's current atexit handlers make unfortunate assumptions
  about process state (specifically stdio) that, coupled with the
  above problems, make it impossible to deal with certain categories
  of error (try "hg status > /dev/full" on a Linux box).

* In Python 3, the atexit implementation is completely hidden, so
  we can't hijack the platform's atexit code to run handlers at a
  time of our choosing.

As a result, here's a perfectly cromulent atexit-like implementation
over which we have control.  This lets us decide exactly when the
handlers run (after each request has completed), and control what
the process state is when that occurs (and afterwards).

Valid URLs are of the form::

  local/filesystem/path[#revision]
  file://local/filesystem/path[#revision]
  http://[user[:pass]@]host[:port]/[path][#revision]
  https://[user[:pass]@]host[:port]/[path][#revision]
  ssh://[user@]host[:port]/[path][#revision]

Paths in the local filesystem can either point to Mercurial
repositories or to bundle files (as created by :hg:`bundle` or
:hg:`incoming --bundle`). See also :hg:`help paths`.

An optional identifier after # indicates a particular branch, tag, or
changeset to use from the remote repository. See also :hg:`help
revisions`.

Some features, such as pushing to http:// and https:// URLs are only
possible if the feature is explicitly enabled on the remote Mercurial
server.

Note that the security of HTTPS URLs depends on proper configuration of
web.cacerts.

Some notes about using SSH with Mercurial:

- SSH requires an accessible shell account on the destination machine
  and a copy of hg in the remote path or specified with as remotecmd.
- path is relative to the remote user's home directory by default. Use
  an extra slash at the start of a path to specify an absolute path::

    ssh://example.com//tmp/repository

- Mercurial doesn't use its own compression via SSH; the right thing
  to do is to configure it in your ~/.ssh/config, e.g.::

    Host *.mylocalnetwork.example.com
      Compression no
    Host *
      Compression yes

  Alternatively specify "ssh -C" as your ssh command in your
  configuration file or with the --ssh command line option.

These URLs can all be stored in your configuration file with path
aliases under the [paths] section like so::

  [paths]
  alias1 = URL1
  alias2 = URL2
  ...

You can then use the alias for any command that uses a URL (for
example :hg:`pull alias1` will be treated as :hg:`pull URL1`).

Two path aliases are special because they are used as defaults when
you do not provide the URL to a command:

default:
  When you create a repository with hg clone, the clone command saves
  the location of the source repository as the new repository's
  'default' path. This is then used when you omit path from push- and
  pull-like commands (including incoming and outgoing).

default-push:
  The push command will look for a path named 'default-push', and
  prefer it over 'default' if both are defined.