Add script to install zsh from source

scripts/install-zsh.sh

@@ -0,0 +1,45 @@
+#! /usr/bin/env bash
+set -e
+
+PREFIX="/opt/zsh"
+
+help() {
+  echo "usage: ./install-zsh.sh <VERSION>"
+}
+
+install() {
+  local version="$1"
+  mkdir -p /tmp/zsh-src
+  cd /tmp/zsh-src
+  if [ ! -d "zsh-${version}" ]; then
+    if [ ! -f "zsh-${version}.tar.gz" ]; then
+      wget "http://downloads.sourceforge.net/project/zsh/zsh/${version}/zsh-${version}.tar.gz"
+    fi
+    tar -zxf "zsh-${version}.tar.gz"
+  fi
+  cd "zsh-${version}"
+  ./configure --prefix="$PREFIX" && make && sudo make install
+}
+
+deps() {
+  sudo apt-get update
+  sudo apt-get install -y \
+       build-essential
+}
+
+main() {
+  local command="$1"
+
+  if [ -z "$command" ]; then
+    echo "$(help)" 1>&2
+    exit 1
+  fi
+
+  if [ "$command" == "deps" ]; then
+    deps
+  else
+    install "$command"
+  fi
+}
+
+main $@