Moving Checkstyle sources from sourceforge to github

Sources: http://sourceforge.net/p/checkstyle/code/ci/default/tree/
Destination: https://github.com/checkstyle

Follow installation steps from "How to convert mercurial to git" manual:  http://codeimpossible.com/2011/12/29/Moving-your-mercurial-repository-to-git/

Command to do clone and convert in same time:

git-hg clone http://hg.code.sf.net/p/checkstyle/code checkstyle-git

Review all participants to find duplicates:
git log --raw | grep "^Author: " | sort | uniq -c

2 Author: Bewied <BenWiederhake.......de>
4 Author: BurnOl <BurnOl@KAZ-027469>
1 Author: convert-repo <devnull@localhost>
1 Author: Lars Kühne <lkuehne>
683 Author: lkuehne <devnull@localhost>
43 Author: mstudman <devnull@localhost>
1054 Author: oburn <devnull@localhost>
9 Author: Oleg Sukhodolsky <o_sukhodolsky>
3 Author: Oliver Burn Cygwin <devnull@localhost>
135 Author: Oliver Burn <devnull@localhost>
288 Author: o_sukhodolsky <devnull@localhost>
410 Author: rickgiles <devnull@localhost>
14 Author: tschneeberger <devnull@localhost>


Create bash file that do squash of authors duplicates - change_names.sh:

#!/usr/bin/bash
   
git filter-branch --tag-name-filter cat --commit-filter '
      if [ "$GIT_AUTHOR_NAME" = "BurnOl" ] && [ "$GIT_AUTHOR_EMAIL" = "BurnOl@KAZ-027469" ]; then
              GIT_AUTHOR_NAME="Oliver Burn";
              GIT_AUTHOR_EMAIL="oliver@.......com";
              GIT_COMMITTER_NAME="Oliver Burn";
              GIT_COMMITTER_EMAIL="oliver@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "convert-repo" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Oliver Burn";
              GIT_AUTHOR_EMAIL="oliver@.......com";
              GIT_COMMITTER_NAME="Oliver Burn";
              GIT_COMMITTER_EMAIL="oliver@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "lkuehne" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Lars Kühne";
              GIT_AUTHOR_EMAIL="lakuehne@.......com";
              GIT_COMMITTER_NAME="Lars Kühne";
              GIT_COMMITTER_EMAIL="lakuehne@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "Lars Kühne" ] && [ "$GIT_AUTHOR_EMAIL" = "lkuehne" ]; then
              GIT_AUTHOR_NAME="Lars Kühne";
              GIT_AUTHOR_EMAIL="lakuehne@.......com";
              GIT_COMMITTER_NAME="Lars Kühne";
              GIT_COMMITTER_EMAIL="lakuehne@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "mstudman" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Michael Studman";
              GIT_AUTHOR_EMAIL="mstudman@.......com";
              GIT_COMMITTER_NAME="Michael Studman";
              GIT_COMMITTER_EMAIL="mstudman@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "Oliver Burn" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Oliver Burn";
              GIT_AUTHOR_EMAIL="oliver@.......com";
              GIT_COMMITTER_NAME="Oliver Burn";
              GIT_COMMITTER_EMAIL="oliver@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "Oliver Burn Cygwin" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Oliver Burn";
              GIT_AUTHOR_EMAIL="oliver@.......com";
              GIT_COMMITTER_NAME="Oliver Burn";
              GIT_COMMITTER_EMAIL="oliver@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "oburn" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Oliver Burn";
              GIT_AUTHOR_EMAIL="oliver@.......com";
              GIT_COMMITTER_NAME="Oliver Burn";
              GIT_COMMITTER_EMAIL="oliver@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "Oleg Sukhodolsky" ] && [ "$GIT_AUTHOR_EMAIL" = "o_sukhodolsky" ]; then
              GIT_AUTHOR_NAME="Oleg Sukhodolsky";
              GIT_AUTHOR_EMAIL="os97673@.......com";
              GIT_COMMITTER_NAME="Oleg Sukhodolsky";
              GIT_COMMITTER_EMAIL="os97673@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "o_sukhodolsky" ] && [ "$GIT_AUTHOR_EMAIL" = "o_sukhodolsky" ]; then
              GIT_AUTHOR_NAME="Oleg Sukhodolsky";
              GIT_AUTHOR_EMAIL="os97673@.......com";
              GIT_COMMITTER_NAME="Oleg Sukhodolsky";
              GIT_COMMITTER_EMAIL="os97673@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "o_sukhodolsky" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Oleg Sukhodolsky";
              GIT_AUTHOR_EMAIL="os97673@.......com";
              GIT_COMMITTER_NAME="Oleg Sukhodolsky";
              GIT_COMMITTER_EMAIL="os97673@.......com";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "rickgiles" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Rick Giles";
              GIT_AUTHOR_EMAIL="rickgiles";
              GIT_COMMITTER_NAME="Rick Giles";
              GIT_COMMITTER_EMAIL="rickgiles";
              git commit-tree "$@";
      elif [ "$GIT_AUTHOR_NAME" = "tschneeberger" ] && [ "$GIT_AUTHOR_EMAIL" = "devnull@localhost" ]; then
              GIT_AUTHOR_NAME="Travis Schneeberger";
              GIT_AUTHOR_EMAIL="leo.herbie@.......com";
              GIT_COMMITTER_NAME="Travis Schneeberger";
              GIT_COMMITTER_EMAIL="leo.herbie@.......com";
              git commit-tree "$@";
      else
              git commit-tree "$@";
      fi' HEAD

explanation to script:
" --tag-name-filter cat" - required to not loose tags after history rewrite.
"GIT_COMMITTER_NAME and GIT_COMMITTER_EMAIL" - to let github show commits correctly at page of commits history, in other case you have invalid-email-address in details for each commmit.

Do changes to authors and do push to remote:
./change_names.sh
git remote add origin git@github.com:checkstyle/checkstyle.git
git push -u origin master --tags

Sources of wisdom:
In filter-branch shell syntax for IF-ELSE should be used - http://www.dreamsyssoft.com/unix-shell-scripting/ifelse-tutorial.php
usage of bash syntax for IF- ELSE cause errors - http://blog.linuxacademy.com/linux/conditions-in-bash-scripting-if-statements/
http://git-scm.com/book/ch6-4.html (chapter "Changing E-Mail Addresses Globally")
http://ayende.com/blog/4532/extracting-a-list-of-committers-from-git