BashChain (#260)

Love the project, a ton of fun!

I think the PR is pretty self-explanatory, happy to make any changes! I
am working on using it in an `LLMBashChain` and may update as that
progresses.

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>

docs/examples/chains/llm_bash.ipynb

@@ -0,0 +1,86 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# LLM Chain\n",
+    "This notebook showcases using LLMs and a bash process to do perform simple filesystem commands."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      "\n",
+      "\u001b[1m> Entering new LLMBashChain chain...\u001b[0m\n",
+      "Please write a bash script that prints 'Hello World' to the console.\u001b[32;1m\u001b[1;3m\n",
+      "\n",
+      "```bash\n",
+      "echo \"Hello World\"\n",
+      "```\u001b[0m\n",
+      "Answer: \u001b[33;1m\u001b[1;3m{'success': True, 'outputs': ['Hello World\\n']}\u001b[0m\n",
+      "\u001b[1m> Finished LLMBashChain chain.\u001b[0m\n"
+     ]
+    },
+    {
+     "data": {
+      "text/plain": [
+       "{'commands': ['echo \"Hello World\"'],\n",
+       " 'output': {'success': True, 'outputs': ['Hello World\\n']}}"
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "from langchain.chains.llm_bash.base import LLMBashChain\n",
+    "from langchain.llms import OpenAI\n",
+    "\n",
+    "llm = OpenAI(temperature=0)\n",
+    "\n",
+    "text = \"Please write a bash script that prints 'Hello World' to the console.\"\n",
+    "\n",
+    "bash_chain = LLMBashChain(llm=llm, verbose=True)\n",
+    "\n",
+    "bash_chain.run(text)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.9.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}