sebastien / multiplex

Command-line process mutliplexer

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Multiplex is a command-line multiplexer along with a simple Python API to run multiple processes in parallel and stop them all at once, or based on some condition.

Multiplex will gracefully shutdown child processes, and multiplex their output and error streams to stdout and stderr in a way that is easily parsable with regular command line tools.

Multiplex is useful when you need to run multiple programs all at once and combine their output. For instance, you need a webserver, a workqueue and a database to run standalone all together. You could write a shell script, or you could write a one liner using multiplex.

Here's how you'd benchmark Python's embedded HTTP server with a one-liner:

multiplex "|silent=python -m http.server" "+1|end=ab -n1000 http://localhost:8000/"

Installing

Quick, from the shell:

$ curl -o multiplex https://raw.githubusercontent.com/sebastien/multiplex/main/src/py/multiplex.py; chmod +x multiplex
$ ./multiplex --help

alternatively, using pip:

$ python -m pip install --user multiple

Usage

Commands

Here are some example commands that will help understand the syntax:

multiplex "python -m http.server"

Running a command after 5s delay:

multiplex "+5=python -m http.server"

Running a command after another

multiplex "A=python -m http.server" "+A=ab -n1000 http://localhost:8000/"

Commands follow a simple structure:

• Prefix, before the =. If your command has an equal, start with an empty prefix (=echo =)

• Prefix has a name (A=)

• A potential delay (+0.5)

• A potential sequence of actions (|silent|term)

• Naming: A=, B= processes are named in UPPER_CASE

• Delay (seconds): +1 or +1.5 waits delay seconds before starting the process

• Delay (after process): +A wait for A (or any other named process) to end before starting the process

Actions:

• |end, when the process ends, it terminate all other processes
• |silent, the process does not emit anything
• |noout, the process does not emit stdout data
• |noerr, the process does not emit stderr data

Timeout:

• -t|--timeout with a value T in seconds