osx从10.8升级到10.9以后，svn被自动从1.6升级到1.7
公司所有svn版本都是1.6，而svn奇葩的在于，低版本1.6可以使用1.7的内容。而1.7命令行无法读取1.6，提示too old
没办法，手动降级：
开始考虑直接下一个svn1.6的pkg。结果发现安装的时候，选项是灰的
失败
然后想到了homebrew
找到这个http://honglin.info/tools/2013/06/18/install-specific-version-of-tool-with-HomeBrew.html
# update
brew update
# 如果brew update遇到问题，也可以通过以下命令进行更新
cd $(brew --prefix) && git pull --rebase
# 以postgresql为例
brew versions postgresql
# Output:
# 9.1.3 git checkout e088818 /usr/local/Library/Formula/postgresql.rb
# 9.1.2 git checkout dfcc838 /usr/local/Library/Formula/postgresql.rb
# 9.1.1 git checkout 4ef8fb0 /usr/local/Library/Formula/postgresql.rb
# 9.0.4 git checkout 2accac4 /usr/local/Library/Formula/postgresql.rb
# 9.0.3 git checkout b782d9d /usr/local/Library/Formula/postgresql.rb
# 9.0.2 git checkout 2c3b88a /usr/local/Library/Formula/postgresql.rb
# 9.0.1 git checkout b7fab6c /usr/local/Library/Formula/postgresql.rb
# 9.0.0 git checkout 1168d8f /usr/local/Library/Formula/postgresql.rb
# 8.4.4 git checkout c32bea0 /usr/local/Library/Formula/postgresql.rb
# 8.4.3 git checkout 9b2ef7c /usr/local/Library/Formula/postgresql.rb
# 8.4.1 git checkout 0495cf5 /usr/local/Library/Formula/postgresql.rb
# 8.4.0 git checkout a82e823 /usr/local/Library/Formula/postgresql.rb
git checkout a82e823 /usr/local/Library/Formula/postgresql.rb
brew install postgresql
[cloudinsky:/usr/local/Library/Formula]$brew versions svn
1.8.3 git checkout 9cd0f34 /usr/local/Library/Formula/subversion.rb
1.8.0 git checkout f56b641 /usr/local/Library/Formula/subversion.rb
1.8.1 git checkout 55577bb /usr/local/Library/Formula/subversion.rb
1.7.10 git checkout 0060dc3 /usr/local/Library/Formula/subversion.rb
1.7.9 git checkout b0e6223 /usr/local/Library/Formula/subversion.rb
1.7.8 git checkout f7a42d2 /usr/local/Library/Formula/subversion.rb
1.7.7 git checkout a6dcc41 /usr/local/Library/Formula/subversion.rb
1.7.6 git checkout 6b8d25f /usr/local/Library/Formula/subversion.rb
1.7.5 git checkout 5d5cd70 /usr/local/Library/Formula/subversion.rb
1.7.4 git checkout dc4245c /usr/local/Library/Formula/subversion.rb
1.7.3 git checkout eb97154 /usr/local/Library/Formula/subversion.rb
1.7.2 git checkout d89bf83 /usr/local/Library/Formula/subversion.rb
1.6.17 git checkout 6e2d550 /usr/local/Library/Formula/subversion.rb
1.6.16 git checkout 83ed494 /usr/local/Library/Formula/subversion.rb
1.6.15 git checkout 809a18a /usr/local/Library/Formula/subversion.rb
1.6.13 git checkout 7871a99 /usr/local/Library/Formula/subversion.rb
1.6.12 git checkout c99b3ac /usr/local/Library/Formula/subversion.rb
1.6.6 git checkout 8774131 /usr/local/Library/Formula/subversion.rb
[cloudinsky:/usr/local/Library/Formula]$git checkout 6e2d550 /usr/local/Library/Formula/subversion.rb
[cloudinsky:/usr/local/Library/Formula]$brew install svn
如果安装失败
Error: Cannot write to /usr/local/Cellar
qgx:svn1.6 gongzuo-qipai$ sudo brew install svn
Password:
Error: Cowardly refusing to `sudo brew install'
You can use brew with sudo, but only if the brew executable is owned by root.
However, this is both not recommended and completely unsupported so do so at
your own risk.
则：
sudo chown root:admin /usr/local/bin/brew
然后再
sudo brew install svn