Fix example

Author: gjbex

hands-on/shell_interaction.ipynb

@@ -165,11 +165,18 @@
    "source": [
     "with open('tmp/date_file.txt', 'w') as file:\n",
     "    for i in range(10):\n",
-    "        print(f'{i} ', end='', file=file)\n",
+    "        print(f'{i} ', end='', file=file, flush=True)\n",
     "        sh.date(_out=file)\n",
     "        sh.sleep('1')"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Note the use of the `flush` optional argument in the print function.  If this is omitted, the Python interpreter will only flush the results of its own print calls after the `sh` modules has written its output."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -220,7 +227,9 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "scrolled": true
+   },
    "outputs": [],
    "source": [
     "sh.grep(sh.ls('-l'), r'\\.ipynb$')"
@@ -241,16 +250,7 @@
    },
    "outputs": [],
    "source": [
-    "sh.sort(sh.cut('-d', ' ', '-f', '6', 'tmp/date_file.txt'), '-r')"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "_ = sh.rm('-r', 'tmp')"
+    "sh.sort(sh.cut('-d', ' ', '-f', '5', 'tmp/date_file.txt'), '-r')"
    ]
   },
   {
@@ -512,7 +512,7 @@
    },
    "outputs": [],
    "source": [
-    "p1 = subprocess.Popen(['cut', '-d', ' ', '-f', '6', 'tmp/data.txt'], stdout=subprocess.PIPE)\n",
+    "p1 = subprocess.Popen(['cut', '-d', ' ', '-f', '5', 'tmp/data.txt'], stdout=subprocess.PIPE)\n",
     "p2 = subprocess.Popen(['sort', '-r'], stdin=p1.stdout, stdout=subprocess.PIPE, encoding='utf8')\n",
     "p1.stdout.close()\n",
     "output, _ = p2.communicate()\n",