Aexpect: Control your interactive applications

This project provides services similar to the pexpect python library, so to speak, spawn and control interactive applications, such as ssh, sftp and others although it can be useful for pure streams as well.

It's enhanced with multi-pattern matching, convenience features for not-only-linux terminals as well as support for terminals that "spit" extra output from time to time (eg. kernel messages) over the output.

There are also extra classes to simplify executing parts of a program on a different location (distributed programming) or writing controls executed on another host (metaprogramming).

Simple usage

>>> import aexpect
>>> import time
>>> dir(aexpect)
['Expect', 'ExpectError', 'ExpectProcessTerminatedError', 'ExpectTimeoutError', 'ShellCmdError', 'ShellError', 'ShellProcessTerminatedError', 'ShellSession', 'ShellStatusError', 'ShellTimeoutError', 'Spawn', 'Tail', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', 'client', 'exceptions', 'kill_tail_threads', 'remote', 'rss_client', 'run_bg', 'run_fg', 'run_tail', 'shared', 'utils']
>>> session = aexpect.ShellSession("bash")
>>> session.cmd("ls /tmp/b")
'1  2\n'
>>> session.cmd("cat /tmp/b/1")
'Hello\n'
>>> session.cmd("cat /tmp/b/2")
'World\n'
>>> dir(session)
['_ShellSession__RE_STATUS', '__class__', '__del__', '__delattr__', '__dict__', '__dir__', '__doc__', '__enter__', '__eq__', '__exit__', '__format__', '__ge__', '__getattribute__', '__getinitargs__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_add_close_hook', '_add_reader', '_aexpect_helper', '_close_aexpect_helper', '_close_reader_fds', '_get_fd', '_join_thread', '_read_nonblocking', '_start_thread', '_tail', 'a_id', 'auto_close', 'close', 'close_hooks', 'closed', 'cmd', 'cmd_output', 'cmd_output_safe', 'cmd_status', 'cmd_status_output', 'command', 'ctrlpipe_filename', 'echo', 'encoding', 'get_command_output', 'get_command_status', 'get_command_status_output', 'get_id', 'get_output', 'get_pid', 'get_status', 'get_stripped_output', 'inpipe_filename', 'is_alive', 'is_defunct', 'is_responsive', 'kill', 'linesep', 'lock_client_starting_filename', 'lock_server_running_filename', 'log_file', 'log_file_fd', 'match_patterns', 'match_patterns_multiline', 'output_filename', 'output_func', 'output_params', 'output_prefix', 'prompt', 'read_nonblocking', 'read_until_any_line_matches', 'read_until_last_line_matches', 'read_until_last_word_matches', 'read_until_output_matches', 'read_up_to_prompt', 'reader_fds', 'reader_filenames', 'readers', 'remove_command_echo', 'remove_last_nonempty_line', 'send', 'send_ctrl', 'sendcontrol', 'sendline', 'server_log_filename', 'set_linesep', 'set_log_file', 'set_output_func', 'set_output_params', 'set_output_prefix', 'set_prompt', 'set_status_test_command', 'set_termination_func', 'set_termination_params', 'shell_pid_filename', 'status_filename', 'status_test_command', 'tail_thread', 'termination_func', 'termination_params', 'thread_name']
>>> session.sendline("for I in $(seq 10); do echo $I; sleep 1; done")
>>> session.read_nonblocking(0.1, 2)
>>> time.sleep(10)
>>> session.read_nonblocking(0.1, 2)
'2\n3\n4\n5\n6\n7\n8\n9\n10\n[medic@fedora ~ \x1b[1;31m\x1b[0m]$ '
>>> session.sendline("for I in $(seq 10); do echo $I; sleep 1; done")
>>> session.read_nonblocking(1.5, 2)
'1\n2\n3\n4\n'
>>> session.sendline("for I in $(seq 10); do echo $I; sleep 1; done")
>>> session.read_until_output_matches("3", timeout=10)
(0, '1\n2\n3\n')
>>> session.sendline("for I in $(seq 10); do echo $I; sleep 1; done")
>>> session.read_until_output_matches(["5", "7", "2", "foo"], timeout=10)
(2, '1\n2\n')
>>> session.cmd_status("true")
0
>>> session.cmd_status("false")
1
>>> session.is_alive()
True
>>> session.is_responsive()
True
>>> session.sendline("exit")
>>> session.is_alive()
False
>>> session.is_responsive()
False

Debugging

Using this even for purely bash-like constructs is good as you can leverage the python debugger to interactively walk your issues. Especially the pydevd project is great as you can debug code from multiple machines on in a single Eclipse to see concurency issues. Execution is as simple as pip install pydevd on all machines, adding pydevd.settrace(eclipse_machine_ip, True, True) directly into the code replacing the eclipse_machine_ip with IP address of the machine where Eclipse will be running (eg. 127.0.0.1 for localhost). The following True are to redirect stdout/stderr which is usually useful but sometimes might lead to issues. Then you need to start the python debugger inside Eclipse by entering debug view and starting the pydev server pydev->Start debug server. Now you are ready and simply execute your application the way you are used to, once it reaches the pydev.settrace line it will dial to the Eclipse server and show up in your debug view, showing the code you are debugging even though it's on a different machine, allowing you to single-step across multiple processes.