subprocess

Subprocess management: spawn new processes, connect to their pipes, and obtain return codes.

import subprocess

Constants

Name	Type	Description
pipe	int	Requests that a standard stream be redirected through a pipe.
stdout	int	Requests that stderr be merged into stdout.
devnull	int	Requests that a standard stream be redirected to the null device.

Functions

subprocess.run(args: list[str], capture_output: bool = False, text: bool = True, check: bool = False, timeout: float | None = None, input: str | None = None, cwd: str | None = None, env: dict[str, str] | None = None, shell: bool = False, stdin: int = 0, stdout: int = 0, stderr: int = 0) -> CompletedProcess

Runs a command, waits for it to finish, and returns a CompletedProcess.

subprocess.check_output(args: list[str], text: bool = True, timeout: float | None = None, input: str | None = None, cwd: str | None = None, env: dict[str, str] | None = None, shell: bool = False, stderr: int = 0) -> str

Runs a command and returns its standard output.

subprocess.check_call(args: list[str], timeout: float | None = None, cwd: str | None = None, env: dict[str, str] | None = None, shell: bool = False) -> int

Runs a command and raises if it exits with a non-zero status.

CompletedProcess

Represents the result of a finished subprocess.

Properties

Name	Type	Description
args	list[str]	Gets the command arguments used to launch the process.
returncode	int	Gets the process exit status.
stdout	str | None	Gets the captured standard output, if any.
stderr	str | None	Gets the captured standard error, if any.

check_returncode()

Raises CalledProcessError if the process exited with a non-zero status.

SubprocessError

Base exception for subprocess-related failures.

CalledProcessError

Base exception for subprocess-related failures.

Properties

Name	Type	Description
returncode	int	Gets the process exit status.
cmd	list[str]	Gets the command that was run.
output	str | None	Gets the captured standard output, if any.
stderr	str | None	Gets the captured standard error, if any.

TimeoutExpired

Base exception for subprocess-related failures.

Properties

Name	Type	Description
cmd	list[str]	Gets the command that timed out.
timeout	float	Gets the timeout value in seconds.
output	str | None	Gets the captured standard output, if any.
stderr	str | None	Gets the captured standard error, if any.

Popen

Starts and manages a child process like Python's subprocess.Popen.

Properties

Name	Type	Description
pid	int	Gets the operating system process identifier.
args	list[str]	Gets the command arguments used to start the process.
stdin	StreamWriter | None	Gets the redirected standard input writer, if available.
stdout_stream	StreamReader | None	Gets the redirected standard output reader, if available.
stderr_stream	StreamReader | None	Gets the redirected standard error reader, if available.

wait(timeout: float | None = None) -> int

Waits for the process to exit and returns its exit code.

poll() -> int | None

Checks whether the process has exited without blocking.

kill()

Forcefully terminates the child process.

terminate()

Terminates the child process.

send_signal(signal: int)

Sends a signal to the child process.