Contrib Commands

Contrib is an sh sub-module that provides friendly wrappers to useful commands. Typically, the commands being wrapped are unintuitive, and the contrib version makes them intuitive.

Note

Contrib commands should be considered generally unstable. They will grow and change as the community figures out the best interface for them.

Commands

Sudo

Allows you to enter your password from the terminal at runtime, or as a string in your script.

sudo(password=None, *args, **kwargs)

Call sudo with password, if specified, else ask the executing user for a password at runtime via getpass.getpass().

See also

sh.contrib.sudo

Git

Many git commands use a pager for output, which can cause an unexpected behavior when run through sh. To account for this, the contrib version sets _tty_out=False for all git commands.

git(*args, **kwargs)

Call git with STDOUT connected to a pipe, instead of a TTY.

from sh.contrib import git
repo_log = git.log()

SSH

New in version 1.13.0.

SSH password-based logins can be a pain. This contrib command performs all of the ugly setup and provides a clean interface to using SSH.

ssh(interact=None, password=None, prompt_match=None, login_success=None, *args, **kwargs)
Parameters
  • interact – A callback to handle SSH session interaction after login is successful. Required.

  • password – A password string or a function that returns a password string. Optional. If not provided, getpass.getpass() is used.

  • prompt_match – The string to match in order to determine when to provide SSH with the password. Or a function that matches on the output. Optional.

  • login_success – A function to determine if SSH login is successful. Optional.

The interact parameter takes a callback with a signature that is slightly different to the function callbacks for redirection:

fn(content, stdin_queue)
Parameters
  • content – An instance of an ephemeral SessionContent class whose job is to hold the characters that the SSH session has written to STDOUT.

  • stdin_queue – A queue.Queue object to communicate with STDIN programmatically.

password can be simply a string that will be used to type the password. If it’s not provided, it will be read from STDIN at runtime via getpass.getpass(). It can also be a callable that returns the password string.

prompt_match is a string to match before the contrib command will provide the SSH process with the password. It is optional, and if left unspecified, will default to “password: “. It can also be a callable that is called on a SessionContent instance and returns True or False for a match.

login_success is a function that takes a SessionContent object and returns a boolean for whether or not a successful login occurred. It is optional, and if unspecified, simply evaluates to True, meaning any password submission results in a successful login (obviously not always correct). It is recommended that you specify this.

class SessionContent

This class contains a record lines and characters written to the SSH processes’s STDOUT. It should be all you need from the callbacks to determine how to interact with the SSH process.

SessionContent.chars
Type

collections.deque

The previous 50,000 characters.

SessionContent.lines
Type

collections.deque

The previous 5,000 lines.

SessionContent.line_chars
Type

list

The characters in the line currently being aggregated.

SessionContent.cur_line
Type

string

A string of the line currently being aggregated.

SessionContent.last_line
Type

string

The previous line.

SessionContent.cur_char
Type

string

The currently written character.

Extending

For developers.

To extend contrib, simply decorate a function in sh with the @contrib decorator, and pass in the name of the command you wish to shadow to the decorator. This method must return an instance of Command:

@contrib("ls")
def my_ls(original):
    ls = original.bake("-l")
    return ls

Now you can run your custom contrib command from your scripts, and you’ll be using the command returned from your decorated function:

from sh.contrib import ls

# executing: ls -l
print(ls("/"))

For even more flexibility, you can design your contrib command to rewrite its options based on executed arguments. For example, say you only wish to set a command’s argument if another argument is set. You can accomplish it like this:

@contrib("ls")
def my_ls(original):
    def process(args, kwargs):
        if "-a" in args:
            args.append("-L")
        return args, kwargs

    ls = original.bake("-l")
    return ls, process

Returning a process function along with the command will tell sh to use that function to preprocess the arguments at execution time using the _arg_preprocess special kwarg.