Added zsh improvements from work laptop and a doc

home_zsh/.zsh/functions/update_current_git_vars

@@ -0,0 +1,37 @@
+#  This file is used to set a few environment variables which will make it easy to build up our prompt
+# http://sebastiancelis.com/2009/11/16/zsh-prompt-git-users/
+
+unset __CURRENT_GIT_BRANCH
+unset __CURRENT_GIT_BRANCH_STATUS
+unset __CURRENT_GIT_BRANCH_IS_DIRTY
+
+local st="$(git status 2>/dev/null)"
+
+if [[ -n "$st" ]]; then
+    local -a arr
+    arr=(${(f)st})
+    if [[ $arr[1] =~ 'Not currently on any branch.' ]]; then
+        __CURRENT_GIT_BRANCH='no-branch'
+    else
+        __CURRENT_GIT_BRANCH="${arr[1][(w)4]}";
+    fi
+
+    if [[ $st =~ 'nothing to commit, working directory clean' ]]; then
+        __CURRENT_GIT_BRANCH_IS_CLEAN='1'
+    fi
+
+    if [[ $arr[2] =~ 'Your branch is' ]]; then
+        if [[ $arr[2] =~ 'ahead' ]]; then
+            __CURRENT_GIT_BRANCH_STATUS='ahead'
+        elif [[ $arr[2] =~ 'diverged' ]]; then
+            __CURRENT_GIT_BRANCH_STATUS='diverged'
+        else
+            __CURRENT_GIT_BRANCH_STATUS='behind'
+        fi
+    fi
+
+    if [[ ! $st =~ 'nothing to commit' ]]; then
+        __CURRENT_GIT_BRANCH_IS_DIRTY='1'
+    fi
+
+fi