subprocess.SubprocessError: Exception occurred in preexec_fn.

Hello! I'm trying to run xonsh shell using rustpython on Mac but faced with error:

xonsh
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh  # https://rustup.rs/
# restart shell
cargo install --features=ssl --git https://github.com/RustPython/RustPython rustpython
$PATH.append(p'~/.cargo/bin')
#rustpython -m site  # to get locations
rustpython --install-pip
rustpython -m pip install xonsh

Note! No prompt-toolkit as workaround #6487

~/.local/bin/xonsh --no-rc --no-env
# Skipping setup. Because no `readline` implementation available.
$XONSH_SHOW_TRACEBACK = True
ls

Result:

xonsh: To log full traceback to a file set: $XONSH_TRACEBACK_LOGFILE = <filename>
Traceback (most recent call last):
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/pipelines.py", line 177, in __init__
    proc = spec.run(pipeline_group=pipeline_group)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 528, in run
    p = self._run_binary(kwargs)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 585, in _run_binary
    raise xt.XonshError(e) from ex
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 546, in _run_binary
    p = self.cls(cmd, bufsize=bufsize, **kwargs)
  File "/Users/pc/.cargo/git/checkouts/rustpython-63090cdce5e18442/7c3bc5e/crates/pylib/Lib/subprocess.py", line 1062, in __init__
    raise
  File "/Users/pc/.cargo/git/checkouts/rustpython-63090cdce5e18442/7c3bc5e/crates/pylib/Lib/subprocess.py", line 1034, in __init__
    start_new_session, process_group)
  File "/Users/pc/.cargo/git/checkouts/rustpython-63090cdce5e18442/7c3bc5e/crates/pylib/Lib/subprocess.py", line 1958, in _execute_child
    raise child_exception_type(err_msg)
subprocess.SubprocessError: Exception occurred in preexec_fn.

For community

⬇️ Please click the 👍 reaction instead of leaving a +1 or 👍 comment

📝 CodeRabbit Plan Mode

Generate an implementation plan and prompts that you can use with your favorite coding agent.

Create Plan

Examples

🔗 Similar Issues

Related Issues

🔗 Related PRs

#6187 - Handle OsError in REPL [merged]

👤 Suggested Assignees

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!

a20f2cc will fix it. included in #6484

@youknowone

@youknowone I've tested and now it works better:

cargo install --features=ssl --git https://github.com/youknowone/RustPython --branch os rustpython
~/.local/bin/xonsh --no-rc --no-env
$XONSH_SHOW_TRACEBACK = True
ls
# Documents Downloads ...

And after the list of files:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/built_ins.py", line 271, in subproc_captured_hiddenobject
    return xonsh.procs.specs.run_subproc(cmds, captured="hiddenobject", envs=envs)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 1135, in run_subproc
    return _run_specs(specs, cmds)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 1162, in _run_specs
    cp = _run_command_pipeline(specs, cmds)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/specs.py", line 1141, in _run_command_pipeline
    cp = HiddenCommandPipeline(specs)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/pipelines.py", line 190, in __init__
    if update_process_group(pipeline_group, background):
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/pipelines.py", line 91, in update_process_group
    return xj.give_terminal_to(pipeline_group)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/jobs.py", line 329, in give_terminal_to
    _pthread_sigmask(signal.SIG_SETMASK, oldmask)
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/jobs.py", line 327, in give_terminal_to
    raise
  File "/Users/pc/.local/lib/rustpython3.13/site-packages/xonsh/procs/jobs.py", line 309, in give_terminal_to
    os.tcsetpgrp(FD_STDERR, pgid)
AttributeError: module 'os' has no attribute 'tcsetpgrp'

Both fixed by #6484

Navigation Menu

Repository navigation

subprocess.SubprocessError: Exception occurred in preexec_fn. #6489

For community

📝 CodeRabbit Plan Mode

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

subprocess.SubprocessError: Exception occurred in preexec_fn. #6489

Description

For community

Activity

coderabbitai commented on Dec 24, 2025

📝 CodeRabbit Plan Mode

youknowone commented on Dec 24, 2025

anki-code commented on Dec 24, 2025

youknowone commented on Dec 25, 2025

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions