logproc 0.2.0

Run a process and log stdin and stdout.

logproc

Run a process and log stdin and stdout.

Description

This experimental module offers a function execute() that runs a commandline in a subprocess and separately live captures the called process’s standard output and standard error. By default, the output is logged at different levels, but it is possible to provide a callback for different handling.

Usage

In the simplest case, just run execute(["ls", "-l"]), which will run ls -l and log its output with Python’s default logging system, using the logger id ls and the level INFO for stdout, WARNING for stderr.

If you need further customization, here are the two API functions of this module:

execute

def execute(cmd: Sequence[str],
            stdout: OutputHandler | None = None,
            stdout_level: int = logging.INFO,
            stderr: OutputHandler | None = None,
            stderr_level: int = logging.WARNING,
            cwd=None) -> int

Run the given command and log its output as it appears.

Arguments

• cmd - A list of arguments, as in subprocess.run etc.

• stdout, stderr: Handlers for the specified stream. Each of these can be:

  • None (the default) to use the default settings
  • a logger name
  • a logging.Logger
  • a callback

  You can use proc_logger to build a suitable callback.

• stdout_level, stderr_level: Logging levels for the specific output.

Returns

the command’s exit code

Description

execute runs the given command and waits for it to finish. While it is running, its stdout and stderr streams are monitored. Each new line appearing on these streams are immediately handled.

The default handlers will log the message from the subprocess to a logger that logs using the first member of the cmd sequence as a logger name and logging.INFO for stdout and logging.WARNING for stderr output.

proc_logger

def proc_logger(prefix: str = "",
                level: int = logging.INFO,
                logger: LoggerSpec = None,
                extra=None) -> OutputCallback

Creates a callback for execute() that logs to a logger.

Arguments

• prefix - String that will be prepended to each line
• logger - If given, this is either a logger or the name of a logger. If missing, we log to the root logger.
• level - The level at which to log the messages.
• extra - an optional dictionary with extra attributes that gets past on with each log entry