-# Figure out where to get the other repositories from,
-# based on where this GHC repo came from.
-my $defaultrepo = `cat _darcs/prefs/defaultrepo`;
-chomp $defaultrepo;
-my $defaultrepo_base;
-my $checked_out_tree;
-
-if ($defaultrepo =~ /^...*:/) {
- # HTTP or SSH
- # Above regex says "at least two chars before the :", to avoid
- # catching Win32 drives ("C:\").
- $defaultrepo_base = $defaultrepo;
- $defaultrepo_base =~ s#/[^/]+/?$##;
- $checked_out_tree = 0;
-}
-elsif ($defaultrepo =~ /^\/|\.\.\/|.:(\/|\\)/) {
- # Local filesystem, either absolute or relative path
- # (assumes a checked-out tree):
- $defaultrepo_base = $defaultrepo;
- $checked_out_tree = 1;
-}
-else {
- die "Couldn't work out defaultrepo";
-}
+# Usage:
+#
+# ./darcs-all [-q] [-s] [-i] [-r repo]
+# [--nofib] [--testsuite] [--checked-out] cmd [darcs flags]
+#
+# Applies the darcs command "cmd" to each repository in the tree.
+#
+# e.g.
+# ./darcs-all -r http://darcs.haskell.org/ghc get
+# To get any repos which do not exist in the local tree
+#
+# ./darcs-all -r ~/ghc-validate push
+# To push all your repos to the ~/ghc-validate tree
+#
+# ./darcs-all pull -a
+# To pull everything from the default repos
+#
+# ./darc-all push --dry-run
+# To see what local patches you have relative to the main repos
+#
+# -------------- Flags -------------------
+# -q says to be quite, and -s to be silent.
+#
+# -i says to ignore darcs errors and move on to the next repository
+#
+# -r repo says to use repo as the location of package repositories
+#
+# --checked-out says that the remote repo is in checked-out layout, as
+# opposed to the layout used for the main repo. By default a repo on
+# the local filesystem is assumed to be checked-out, and repos accessed
+# via HTTP or SSH are assumed to be in the main repo layout; use
+# --checked-out to override the latter.
+#
+# --nofib, --testsuite also get the nofib and testsuite repos respectively
+#
+# The darcs get flag you are most likely to want is --complete. By
+# default we pass darcs the --partial flag.
+#
+# ------------ Which repos to use -------------
+# darcs-all uses the following algorithm to decide which remote repos to use
+#
+# It always computes the remote repos from a single base, $repo_base
+# How is $repo_base set?
+# If you say "-r repo", then that's $repo_base
+# othewise $repo_base is set thus:
+# look in _darcs/prefs/defaultrepo,
+# and remove the trailing 'ghc'
+#
+# Then darcs-all iterates over the package found in the file
+# ./packages, which has entries like:
+# libraries/array packages/array darcs
+# or, in general
+# <local-path> <remote-path> <vcs>
+#
+# If $repo_base looks like a local filesystem path, or if you give
+# the --checked-out flag, darcs-all works on repos of form
+# $repo_base/<local-path>
+# otherwise darcs-all works on repos of form
+# $repo_base/<remote-path>
+# This logic lets you say
+# both darcs-all -r http://darcs.haskell.org/ghc-6.12 pull
+# and darcs-all -r ../HEAD pull
+# The latter is called a "checked-out tree".
+
+# NB: darcs-all *ignores* the defaultrepo of all repos other than the
+# root one. So the remote repos must be laid out in one of the two
+# formats given by <local-path> and <remote-path> in the file 'packages'.
+
+
+$| = 1; # autoflush stdout after each print, to avoid output after die
+
+my $defaultrepo;