OptionalcwdWorking directory used to resolve command-line paths and execute tools.
OptionalenvEnvironment supplied to the process or read for option defaults.
OptionalmaxKeep at most this many bytes of stdout and of stderr (0 or unset: all); the rest is dropped and truncated set.
OptionalonCalled for each decoded stderr chunk.
OptionalonCalled for each decoded stdout chunk.
OptionalsignalAbort the process tree (SIGTERM, then SIGKILL after a short grace period).
OptionalstdinFed to the tool's stdin, which is closed otherwise.
OptionalstdoutHow stdout is kept: 'text' (default) as a string, 'buffer' as bytes in
stdoutBuffer for binary output, or 'stream' not at all: read it from
start()'s stdout as the tool writes it.
OptionaltimeoutKill the tool and its process tree after this long; 0 or unset waits forever.
Environment, working directory, input/output handling, timeout, and cancellation for an executable.