$ cd ~/z/repo_1_ruby_193/
23:23:57 durrantm Castle2012 /home/durrantm/z/repo_1_ruby_193
$ BASE="~/z"
23:24:03 durrantm Castle2012 /home/durrantm/z/repo_1_ruby_193
$ cd $BASE/repo_1_ruby_193
-bash: cd: ~/z/repo_1_ruby_193: No such file or directory
23:24:25 durrantm Castle2012 /home/durrantm/z/repo_1_ruby_193