To run echo locally:
.. code-block:: python
import spur
shell = spur.LocalShell()
result = shell.run(["echo", "-n", "hello"])
print(result.output) # prints helloExecuting 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
LocalShell
Takes no arguments:
.. code-block:: python
spur.LocalShell()
SshShellRequires 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 errorspur.ssh.MissingHostKey.warn -- accept the host key and log a
warningspur.ssh.MissingHostKey.accept -- accept the host keyshell_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" "bob@proxy.example.com nc -q0 target.example.com 22" )
Examples of socket-like objects include:
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
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 ``ExecutionResult``.
.. code-block:: python
result = shell.run(["echo", "-n", "hello"])
print(result.output) # prints hello
Note that arguments are passed without any shell expansion. For
instance, ``shell.run(["echo", "$PATH"])`` will print the literal string
``$PATH`` rather than the value of the environment variable ``$PATH``.
Raises ``spur.NoSuchCommandError`` if trying to execute a non-existent
command.
Raises ``spur.CouldNotChangeDirectoryError`` if changing the current directory
to ``cwd`` failed.
Optional arguments:
* ``cwd`` -- change the current directory to this value before
executing the command.
* ``update_env`` -- a ``dict`` containing 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 ``True`` when calling ``spawn``, store the
process id of the spawned process as the attribute ``pid`` on the
returned process object. Has no effect when calling ``run``.
* ``allow_error`` -- ``False`` by 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
``stdout`` using ``stdout.write``.
* ``stderr`` -- if not ``None``, anything the command prints to
standard error during its execution will also be written to
``stderr`` using ``stderr.write``.
* ``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 ``stdout`` and ``stderr`` arguments (if set)
and before setting the output attributes on the result.
``shell.run(*args, **kwargs)`` should behave similarly to
``shell.spawn(*args, **kwargs).wait_for_result()``
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.
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.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()
RunProcessErrorA subclass of RuntimeError with the same properties as
ExecutionResult:
return_code -- the return code of the commandoutput -- a string containing the result of capturing stdoutstderr_output -- a string containing the result of capturing
stdoutNoSuchCommandError
``NoSuchCommandError`` has the following properties:
* ``command`` -- the command that could not be found
CouldNotChangeDirectoryErrorCouldNotChangeDirectoryError has the following properties:
directory -- the directory that could not be changed toUsing 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``Try using "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 SSHIf 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"])