shx 0.4.2

For writing async script with Python

shx

Inspired by zx

#!/usr/bin/env shx

await $"cat setup.py | grep name"

branch = await $("git branch --show-current", capture='o')
await $f"dep deploy --branch={branch}"

await gather(
  $"sleep 1; echo 1",
  $"sleep 2; echo 2",
  $"sleep 3; echo 3",
)

name = "foo bar"
await $f"mkdir /tmp/{Q(name)}"

(Take a look at more examples.)

shx makes your script writing experience better by taking the advantages of Python's sugary syntax, AsyncIO, and the extensive Python ecosystem. shx does three things:

1. Wrap asyncio.create_subprocess_shell around with a syntax sugar. await $"command" returns an asyncio.subprocess.Process instance; on non-zero return code, raise subprocess.CalledProcessError.
2. Provide a top-level async environment.
3. Preload commonly used imports and utilities. Currently, the imports are:

import asyncio
from asyncio import *
from pathlib import Path
from shlex import quote as Q
import shutil

Note that shx does not perform quote escape automatically. Use function Q (alias of shlex.quote) to escape unsafe arguments.

Install

pip install shx

Settings and utility functions

Settings can either be task local (e.g. __.trace = True) or per-command (e.g. await $("echo 42", trace=True)):

• shell (Default: $(which bash)): Shell to be used.
• prefix (Default: set -euo pipefail;): String to be prepended to a command.
• trace (Default: True): Display command if set to True. Same as set -x in bash.
• capture (Default: False): If set to True, capture stdout and stderr instead of displaying them. The captured strings will replace the .stdout and .stderr attributes of the asyncio.subprocess.Process instance returned. await $("...", capture='o') and await $("...", capture='e') are the aliases of (await $("...", capture=True)).stdout and (await $("...", capture=True)).stderr, respectively.

Attributes:

• __.argv: alias of sys.argv, a list of command line arguments
• __.env: alias of os.environ, a dict of environment variables

cd(cwd: str)

Change working directory to cwd. Same as the task local settings, the changes are only effective within the current task.

question(prompt: str)

input() with KeyboardInterrupt handling.

About the subprocess syntax

No magic, no meta-programming, and no hacking, whatsoever. Prior execution, the script is tokenized, and the following replacements occur:

• "str prefix" $"command" -> SHX("command")
• "function" $("command", k1=v1, ...) -> SHX("command", k1=v1, ...)

where SHX is an async function wrapping around asyncio.create_subprocess_shell.