Source code for

Shell commands like git, django-admin etc.

import functools
import os
import shlex
import shutil
import subprocess
import sys
from functools import lru_cache
from pathlib import Path
from typing import Callable, Dict, Iterable, Iterator, List, Optional, Union

from .exceptions import ShellCommandException
from .log import logger

PathLike = Union[str, os.PathLike]

IS_POSIX = == "posix"
IS_WINDOWS = sys.platform == "win32"

# The following default flags were borrowed from Github's docs:
EDITORS: Dict[str, List[str]] = {
    # -- $EDITOR and $VISUAL should be considered first --
    # Terminal based
    "sensible-editor": [],  # default editor in Debian-based systems like Ubuntu
    "nvim": [],  # if a person has nvim installed, chances are they like it as EDITOR
    "nano": [],  # beginner-friendly, vim users will likely have EDITOR=vim already set
    "vim": [],
    # GUI
    "subl": ["-w"],
    "code": ["--wait"],
    "mate": ["-w"],  # OS X specific
    "atom": ["--wait"],
    # Fallbacks (we tried reasonably hard to find a good editor...)
    "notepad": [],  # Windows
    "vi": [],  # POSIX
"""Programs to be tried (in sequence) when calling :obj:`edit` and :obj:`get_editor` in
the case the environment variables EDITOR and VISUAL are not set.

_GIT_CMD = "git"
_GIT_CMD_WIN = "git.exe"

[docs]class ShellCommand: """Shell command that can be called with flags like git('add', 'file') Args: command: command to handle shell: run the command in the shell (``True`` by default). cwd: current working dir to run the command The produced command can be called with the following keyword arguments: - **pretend** (*bool*): skip execution (but log) when pretending. ``False`` by default. The positional arguments are passed to the underlying shell command. In the case the path to the executable contains spaces of any other special shell character, ``command`` needs to be properly quoted. """ def __init__( self, command: str, shell: bool = True, cwd: Optional[str] = None, ): self._command = command self._shell = shell self._cwd = cwd
[docs] def run(self, *args, **kwargs) -> subprocess.CompletedProcess: """Execute command with the given arguments via :obj:``.""" command = f"{self._command} {join(args)}".strip()"run", command, context=self._cwd) should_pretend = kwargs.pop("pretend", False) if should_pretend: return subprocess.CompletedProcess(command, 0, None, None) opts: dict = { "shell": self._shell, "cwd": self._cwd, "stdout": subprocess.PIPE, "stderr": subprocess.STDOUT, "universal_newlines": True, "env": { **os.environ, # try to disable i18n **dict(LC_ALL="C", LANGUAGE=""), }, **kwargs, # allow overwriting defaults } if self._shell: return, **opts) # ^ `check_output` does not seem to support terminal editors return, posix=IS_POSIX), **opts)
# ^ Joining and then splitting is the only way of supporting all the cases def __call__(self, *args, **kwargs) -> Iterator[str]: """Execute the command, returning an iterator for the resulting text output""" try: completed =*args, **kwargs) except FileNotFoundError as e:"info", f'last command failed with "{e!s}"') raise ShellCommandException(str(e)) from e try: completed.check_returncode() except subprocess.CalledProcessError as e: stdout, stderr = (e or "" for e in (completed.stdout, completed.stderr)) stdout, stderr = (e.strip() for e in (stdout, stderr)) sep = "; " if stdout and stderr else "" msg = sep.join([stdout, stderr])"info", f'last command failed with "{msg}"') raise ShellCommandException(msg) from e return (line for line in (completed.stdout or "").splitlines())
[docs]def shell_command_error2exit_decorator(func: Callable): """Decorator to convert given ShellCommandException to an exit message This avoids displaying nasty stack traces to end-users """ @functools.wraps(func) def func_wrapper(*args, **kwargs): try: func(*args, **kwargs) except ShellCommandException as e: cause = e.__cause__ reason = cause.output if cause and hasattr(cause, "output") else e print(f"{e}:\n{reason}") sys.exit(1) return func_wrapper
# ToDo: Change this to just `cache` from Python 3.9 on.
[docs]@lru_cache(maxsize=None) def get_git_cmd(**args) -> ShellCommand: """Retrieve the git shell command depending on the current platform Args: **args: additional keyword arguments to :obj:`~.ShellCommand` """ if IS_WINDOWS: # pragma: no cover # ^ CI setup does not aggregate Windows coverage for shell in (True, False): cmd = ShellCommand(_GIT_CMD_WIN, shell=shell, **args) try: cmd("--version") except ShellCommandException: continue return cmd # available and works with either shell=True or shell=False return cmd # not available, but we return it anyway for better error messages return ShellCommand(_GIT_CMD, **args)
[docs]def command_exists(cmd: str) -> bool: """Check if command exists Args: cmd: executable name """ return shutil.which(cmd) is not None
[docs]def get_executable( name: str, prefix: PathLike = sys.prefix, include_path=True ) -> Optional[str]: """Find an executable in the system, if available. Args: name: name of the executable prefix: look on this directory, exclusively or in addition to $PATH depending on the value of ``include_path``. Defaults to :obj:`sys.prefix`. include_path: when True the functions tries to look in the entire $PATH. Note: The return value might contain whitespaces. If this value is used in a shell environment, it needs to be quote properly to avoid the underlying shell interpreter splitting the executable path. """ executable = shutil.which(name) if include_path and executable: return executable candidates = list(Path(prefix).resolve().glob(f"*/{name}*")) # ^ this works in virtual envs and both Windows and POSIX if candidates: path = (f.parent for f in sorted(candidates, key=lambda p: len(str(p)))) return shutil.which(name, path=os.pathsep.join(str(p) for p in path)) # ^ which will guarantee we find an executable and not only a regular file return None
[docs]def get_command( name: str, prefix: PathLike = sys.prefix, include_path=True, shell=True, **kwargs ) -> Optional[ShellCommand]: """Similar to :obj:`get_executable` but return an instance of :obj:`ShellCommand` if it is there to be found. Additional kwargs will be passed to the :obj:`ShellCommand` constructor. """ executable = get_executable(name, prefix, include_path) if not executable: return None if shell: executable = join([executable]) kwargs["shell"] = shell return ShellCommand(executable, **kwargs)
[docs]def get_editor(**kwargs) -> str: """Get an available text editor program""" from_env = os.getenv("VISUAL") or os.getenv("EDITOR") if from_env: return from_env # user is responsible for proper quoting candidates = ((get_executable(e), opts) for e, opts in EDITORS.items()) editor, opts = next((c for c in candidates if c[0]), (None, [""])) if editor: return join([editor, *opts]) msg = "No text editor found in your system, please set EDITOR in your environment" raise ShellCommandException(msg)
[docs]def edit(file: PathLike, *args, **kwargs) -> Path: """Open a text editor and returns back a :obj:`Path` to file, after user editing.""" editor = ShellCommand(get_editor()) editor(file, *args, **{"stdout": None, "stderr": None, **kwargs}) # ^ stdout/stderr=None => required for a terminal editor to open properly return Path(file)
[docs]def join(parts: Iterable[Union[str, PathLike]]) -> str: """Join different parts of a shell command into a string, quoting whitespaces.""" if IS_WINDOWS: # pragma: no cover # ^ CI setup does not aggregate Windows coverage return subprocess.list2cmdline(map(str, parts)) return " ".join(shlex.quote(str(p)) for p in parts)
# ^ TODO: Replace with `shlex.join(map(str, parts))` when Python >= 3.8
[docs]def git(*args, **kwargs) -> Iterator[str]: """Command for git""" return get_git_cmd()(*args, **kwargs) # delayed, so errors show up with --verbose
#: Command for python python = ShellCommand(sys.executable)