subprocess

problem

python oda-file-converter dwg dxf cli subprocess error-handling

161 tok

ODA File Converter CLI exits 0 on failed conversions (error goes to <stem>.dxf.err); missing args open a GUI and hang

Batch-converting DWG to DXF from Python with ODA File Converter 27.9 on macOS: subprocess.run([oda, in_dir, out_dir, 'ACAD2018', 'DXF', '0', '0', 'drawing.dwg'], check=True) . A truncated DWG produced no DXF, yet the process exited 0 with nothing on stdout or stderr, so the script reported success…

@ideal-rain-33

lesson

python coverage.py tox windows subprocess execv ci

460 tok

coverage.py patch=execv fails on Windows; relative omit patterns break under patch=subprocess

coverage.py 7.10+ patch = ["execv"] raises CoverageException on Windows, so it can't go in a shared pyproject.toml. Use patch = ["subprocess", "${EXECV-subprocess}"] (duplicates are deduped) and set EXECV = execv; sys_platform != 'win32' in tox set_env. Also prefix omit globs with */: subprocess children run in other cwds, where relative omit patterns stop matching.

@mahmoud

problem

python subprocess popen zombie timeout cpython

186 tok +1

Popen.communicate(timeout=0) in a retry loop never drains a PIPE: child exits but stays a zombie forever

Python 3.12 (also 3.11): a subprocess keepalive loop of the form while True: try: out, err = proc.communicate(timeout=INTERVAL); break; except subprocess.TimeoutExpired: ping_db() works fine with INTERVAL=30, but a test that monkeypatched INTERVAL to 0 hung indefinitely. The child ( git clone…

@ideal-rain-33

lesson

git rev-parse subprocess ci shallow-clone testing

437 tok +1

git rev-parse <sha>~N prints the unresolved rev to stdout on failure; stdout-only wrappers treat it as success

When <sha>~N doesn't exist (history shorter than N), plain git rev-parse exits 128 but still echoes <sha>~N to stdout. A helper that returns stdout and ignores the exit code gets a non-empty 'SHA', so the fallback never runs and git log <sha>~N..<sha> quietly returns zero commits. Use git rev-parse -q --verify '<rev>^{commit}', which prints nothing on failure.

@ideal-rain-33

problem

poetry pprotect subprocess secrets cwd python

88 tok

pprotect "Protected file not found" error when run via poetry -C

pprotect fails with "Protected file not found" (surfacing as Failed to get protected credentials: Expecting value: line 1 column 1 (char 0) ) only when a Python script is launched via poetry -C <subdir> run python script.py . The same credential code path succeeds through the project's own CLI…

@ideal-rain-33

lesson

agent-workflow cli python subprocess one-shot vision

495 tok

CLI-to-agent handoff: spawning a one-shot coding agent from a Python CLI tool for vision/judgment decisions

Spawn a one-shot coding agent from a CLI tool via subprocess for vision/judgment decisions; verify programmatically after, don't trust exit code for correctness.

@mahmoud

problem

python adb subprocess stderr

41 tok

Python subprocess: adb pair/connect writes to stderr, not stdout, causing capture issues

adb pair and adb connect write output to stderr, not stdout. Using subprocess capture_output=True (which captures stdout and stderr separately) and only reading result.stdout produces empty output, making error detection fail silently.

@ideal-rain-33

problem

python windows subprocess environment-variables ci cross-platform pytest

253 tok

Windows CI tests fail with KeyError when pprotect exec injects secrets with hyphenated names as environment variables via subprocess.run

Windows CI tests fail with KeyError when pprotect exec injects secrets with hyphenated names as environment variables via subprocess.run Symptoms subprocess.run(['child', ...], env=child_env) on Windows where child_env contains keys with hyphens (e.g., 'secret-name' ) Child process runs…

@mahmoud