To run echo locally:
.. code-block:: python
import spur shell = spur.LocalShell() result = shell.run(["echo", "-n", "hello"]) print(result.output) # prints hello
Executing the same command over SSH uses the same interface -- the only difference is how the shell is created:
.. code-block:: python
import spur shell = spur.SshShell(hostname="localhost", username="bob", password="password1") with shell: result = shell.run(["echo", "-n", "hello"]) print(result.output) # prints hello
$ pip install spur
Takes no arguments: .. code-block:: python spur.LocalShell() SshShell ~~~~~~~~ Requires a hostname. Also requires some combination of a username, password and private key, as necessary to authenticate: .. code-block:: python # Use a password spur.SshShell( hostname="localhost", username="bob", password="password1" ) # Use a private key spur.SshShell( hostname="localhost", username="bob", private_key_file="path/to/private.key" ) # Use a port other than 22 spur.SshShell( hostname="localhost", port=50022, username="bob", password="password1" ) Optional arguments: * ``connect_timeout`` -- a timeout in seconds for establishing an SSH connection. Defaults to 60 (one minute). * ``missing_host_key`` -- by default, an error is raised when a host key is missing. One of the following values can be used to change the behaviour when a host key is missing: - ``spur.ssh.MissingHostKey.raise_error`` -- raise an error - ``spur.ssh.MissingHostKey.warn`` -- accept the host key and log a warning - ``spur.ssh.MissingHostKey.accept`` -- accept the host key * ``shell_type`` -- the type of shell used by the host. Defaults to ``spur.ssh.ShellTypes.sh``, which should be appropriate for most Linux distributions. If the host uses a different shell, such as simpler shells often found on embedded systems, try changing ``shell_type`` to a more appropriate value, such as ``spur.ssh.ShellTypes.minimal``. The following shell types are currently supported: - ``spur.ssh.ShellTypes.sh`` -- the Bourne shell. Supports all features. - ``spur.ssh.ShellTypes.minimal`` -- a minimal shell. Several features are unsupported: - Non-existent commands will not raise ``spur.NoSuchCommandError``. - The following arguments to ``spawn`` and ``run`` are unsupported unless set to their default values: ``cwd``, ``update_env``, and ``store_pid``. * ``look_for_private_keys`` -- by default, Spur will search for discoverable private key files in ``~/.ssh/``. Set to ``False`` to disable this behaviour. * ``load_system_host_keys`` -- by default, Spur will attempt to read host keys from the user's known hosts file, as used by OpenSSH, and no exception will be raised if the file can't be read. Set to ``False`` to disable this behaviour. * ``sock`` -- an open socket or socket-like object to use for communication to the target host. For instance: .. code-block:: python sock=paramiko.proxy.ProxyCommand( "ssh -q -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" "firstname.lastname@example.org nc -q0 target.example.com 22" ) Examples of socket-like objects include: * |paramiko.Channel|_ * |paramiko.proxy.ProxyCommand|_ (`unsupported in Python 3 <https://github.com/paramiko/paramiko/issues/673>`_ as of writing) .. |paramiko.Channel| replace:: ``paramiko.Channel`` .. _paramiko.Channel: http://docs.paramiko.org/en/latest/api/channel.html .. |paramiko.proxy.ProxyCommand| replace:: ``paramiko.proxy.ProxyCommand`` .. _paramiko.proxy.ProxyCommand: http://docs.paramiko.org/en/latest/api/proxy.html Shell interface --------------- run(command, cwd, update\_env, store\_pid, allow\_error, stdout, stderr, encoding)
Run a command and wait for it to complete. The command is expected to be
a list of strings. Returns an instance of
.. code-block:: python
result = shell.run(["echo", "-n", "hello"]) print(result.output) # prints hello
Note that arguments are passed without any shell expansion. For
shell.run(["echo", "$PATH"]) will print the literal string
$PATH rather than the value of the environment variable
spur.NoSuchCommandError if trying to execute a non-existent
spur.CouldNotChangeDirectoryError if changing the current directory
cwd-- change the current directory to this value before executing the command.
dictcontaining environment variables to be set before running the command. If there's an existing environment variable with the same name, it will be overwritten. Otherwise, it is unchanged.
store_pid-- if set to
spawn, store the process id of the spawned process as the attribute
pidon the returned process object. Has no effect when calling
Falseby default. If
False, an exception is raised if the return code of the command is anything but 0. If
True, a result is returned irrespective of return code.
stdout-- if not
None, anything the command prints to standard output during its execution will also be written to
stderr-- if not
None, anything the command prints to standard error during its execution will also be written to
encoding-- if set, this is used to decode any output. By default, any output is treated as raw bytes. If set, the raw bytes are decoded before writing to the passed
stderrarguments (if set) and before setting the output attributes on the result.
shell.run(*args, **kwargs) should behave similarly to
spawn(command, cwd, update_env, store_pid, allow_error, stdout, stderr, encoding)
Behaves the same as ``run`` except that ``spawn`` immediately returns an object representing the running process. Raises ``spur.NoSuchCommandError`` if trying to execute a non-existent command. Raises ``spur.CouldNotChangeDirectoryError`` if changing the current directory to ``cwd`` failed. open(path, mode="r") ~~~~~~~~~~~~~~~~~~~~ Open the file at ``path``. Returns a file-like object. By default, files are opened in text mode. Appending `"b"` to the mode will open the file in binary mode. For instance, to copy a binary file over SSH, assuming you already have an instance of ``SshShell``: .. code-block:: python with ssh_shell.open("/path/to/remote", "rb") as remote_file: with open("/path/to/local", "wb") as local_file: shutil.copyfileobj(remote_file, local_file) close() ~~~~~~~ Closes and the shell and releases any associated resources. ``close()`` is called automatically when the shell is used as a context manager. Process interface ----------------- Returned by calls to ``shell.spawn``. Has the following attributes: * ``pid`` -- the process ID of the process. Only available if ``store_pid`` was set to ``True`` when calling ``spawn``. Has the following methods: * ``is_running()`` -- return ``True`` if the process is still running, ``False`` otherwise. * ``stdin_write(value)`` -- write ``value`` to the standard input of the process. * ``wait_for_result()`` -- wait for the process to exit, and then return an instance of ``ExecutionResult``. Will raise ``RunProcessError`` if the return code is not zero and ``shell.spawn`` was not called with ``allow_error=True``. * ``send_signal(signal)`` -- sends the process the signal ``signal``. Only available if ``store_pid`` was set to ``True`` when calling ``spawn``. Classes ------- ExecutionResult ~~~~~~~~~~~~~~~ ``ExecutionResult`` has the following properties: * ``return_code`` -- the return code of the command * ``output`` -- a string containing the result of capturing stdout * ``stderr_output`` -- a string containing the result of capturing stdout It also has the following methods: * ``to_error()`` -- return the corresponding RunProcessError. This is useful if you want to conditionally raise RunProcessError, for instance: .. code-block:: python result = shell.run(["some-command"], allow_error=True) if result.return_code > 4: raise result.to_error() RunProcessError ~~~~~~~~~~~~~~~ A subclass of ``RuntimeError`` with the same properties as ``ExecutionResult``: * ``return_code`` -- the return code of the command * ``output`` -- a string containing the result of capturing stdout * ``stderr_output`` -- a string containing the result of capturing stdout NoSuchCommandError ~~~~~~~~~~~~~~~~~~ ``NoSuchCommandError`` has the following properties: * ``command`` -- the command that could not be found CouldNotChangeDirectoryError ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``CouldNotChangeDirectoryError`` has the following properties: * ``directory`` -- the directory that could not be changed to API stability ------------- Using the the terminology from `Semantic Versioning <http://semver.org/spec/v1.0.0.html>`_, if the version of spur is X.Y.Z, then X is the major version, Y is the minor version, and Z is the patch version. While the major version is 0, incrementing the patch version indicates a backwards compatible change. For instance, if you're using 0.3.1, then it should be safe to upgrade to 0.3.2. Incrementing the minor version indicates a change in the API. This means that any code using previous minor versions of spur may need updating before it can use the current minor version. Undocumented features ~~~~~~~~~~~~~~~~~~~~~ Some features are undocumented, and should be considered experimental. Use them at your own risk. They may not behave correctly, and their behaviour and interface may change at any time. Troubleshooting --------------- I get the error "Connection refused" when trying to connect to a virtual machine using a forwarded port on ``localhost``
"127.0.0.1" instead of
"localhost" as the hostname.
I get the error "Connection refused" when trying to execute commands over SSH
Try connecting to the machine using SSH on the command line with the same settings. For instance, if you're using the code: .. code-block:: python shell = spur.SshShell( hostname="remote", port=2222, username="bob", private_key_file="/home/bob/.ssh/id_rsa" ) with shell: result = shell.run(["echo", "hello"]) Try running: .. code-block:: sh ssh bob@remote -p 2222 -i /home/bob/.ssh/id_rsa If the ``ssh`` command succeeds, make sure that the arguments to ``ssh.SshShell`` and the ``ssh`` command are the same. If any of the arguments to ``ssh.SshShell`` are dynamically generated, try hard-coding them to make sure they're set to the values you expect. I can't spawn or run commands over SSH ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If you're having trouble spawning or running commands over SSH, try passing ``shell_type=spur.ssh.ShellTypes.minimal`` as an argument to ``spur.SshShell``. For instance: .. code-block:: python import spur import spur.ssh spur.SshShell( hostname="localhost", username="bob", password="password1", shell_type=spur.ssh.ShellTypes.minimal, ) This makes minimal assumptions about the features that the host shell supports, and is especially well-suited to minimal shells found on embedded systems. If the host shell is more fully-featured but only works with ``spur.ssh.ShellTypes.minimal``, feel free to submit an issue. Why don't shell features such as variables and redirection work? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Commands are run directly rather than through a shell. If you want to use any shell features such as variables and redirection, then you'll need to run those commands within an appropriate shell. For instance: .. code-block:: python shell.run(["sh", "-c", "echo $PATH"]) shell.run(["sh", "-c", "ls | grep bananas"])