Add third_party/pexpect

third_party/pexpect/doc/examples.rst

+Examples
+========
+
+Under the distribution tarball directory you should find an "examples" directory.
+This is the best way to learn to use Pexpect. See the descriptions of Pexpect
+Examples.
+
+`topip.py <https://github.com/pexpect/pexpect/blob/master/examples/topip.py>`_
+  This runs `netstat` on a local or remote server. It calculates some simple
+  statistical information on the number of external inet connections. This can
+  be used to detect if one IP address is taking up an excessive number of
+  connections. It can also send an email alert if a given IP address exceeds a
+  threshold between runs of the script. This script can be used as a drop-in
+  Munin plugin or it can be used stand-alone from cron. I used this on a busy
+  web server that would sometimes get hit with denial of service attacks. This
+  made it easy to see if a script was opening many multiple connections. A
+  typical browser would open fewer than 10 connections at once. A script might
+  open over 100 simultaneous connections.
+
+`hive.py <https://github.com/pexpect/pexpect/blob/master/examples/hive.py>`_
+  This script creates SSH connections to a list of hosts that you provide.
+  Then you are given a command line prompt. Each shell command that you
+  enter is sent to all the hosts. The response from each host is collected
+  and printed. For example, you could connect to a dozen different
+  machines and reboot them all at once.
+
+`script.py <https://github.com/pexpect/pexpect/blob/master/examples/script.py>`_
+  This implements a command similar to the classic BSD "script" command.
+  This will start a subshell and log all input and output to a file.
+  This demonstrates the :meth:`~pexpect.spawn.interact` method of Pexpect.
+
+`ftp.py <https://github.com/pexpect/pexpect/blob/master/examples/ftp.py>`_
+  This demonstrates an FTP "bookmark". This connects to an ftp site;
+  does a few ftp tasks; and then gives the user interactive control over
+  the session. In this case the "bookmark" is to a directory on the
+  OpenBSD ftp server. It puts you in the i386 packages directory. You
+  can easily modify this for other sites. This demonstrates the
+  :meth:`~pexpect.spawn.interact` method of Pexpect.
+
+`monitor.py <https://github.com/pexpect/pexpect/blob/master/examples/monitor.py>`_
+  This runs a sequence of commands on a remote host using SSH. It runs a
+  simple system checks such as uptime and free to monitor the state of
+  the remote host.
+
+`passmass.py <https://github.com/pexpect/pexpect/blob/master/examples/passmass.py>`_
+  This will login to each given server and change the password of the
+  given user. This demonstrates scripting logins and passwords.
+
+`python.py <https://github.com/pexpect/pexpect/blob/master/examples/python.py>`_
+  This starts the python interpreter and prints the greeting message
+  backwards. It then gives the user iteractive control of Python. It's
+  pretty useless!
+
+`ssh_tunnel.py <https://github.com/pexpect/pexpect/blob/master/examples/ssh_tunnel.py>`_
+  This starts an SSH tunnel to a remote machine. It monitors the
+  connection and restarts the tunnel if it goes down.
+
+`uptime.py <https://github.com/pexpect/pexpect/blob/master/examples/uptime.py>`_
+  This will run the uptime command and parse the output into variables.
+  This demonstrates using a single regular expression to match the
+  output of a command and capturing different variable in match groups.
+  The grouping regular expression handles a wide variety of different
+  uptime formats.