os.system -> subprocess (#3955)

Quoting the python library documentation:

> The subprocess module provides more powerful facilities for spawning
> new processes and retrieving their results; using that module is
> preferable to using this function.

Author: achille-fouilleul

manim/utils/tex_file_writing.py

@@ -9,8 +9,8 @@
 from __future__ import annotations
 
 import hashlib
-import os
 import re
+import subprocess
 import unicodedata
 from collections.abc import Iterable
 from pathlib import Path
@@ -114,10 +114,11 @@ def generate_tex_file(
     return result
 
 
-def tex_compilation_command(
+def make_tex_compilation_command(
     tex_compiler: str, output_format: str, tex_file: Path, tex_dir: Path
-) -> str:
-    """Prepares the tex compilation command with all necessary cli flags
+) -> list[str]:
+    """Prepares the TeX compilation command, i.e. the TeX compiler name
+    and all necessary CLI flags.
 
     Parameters
     ----------
@@ -132,40 +133,36 @@ def tex_compilation_command(
 
     Returns
     -------
-    :class:`str`
+    :class:`list[str]`
         Compilation command according to given parameters
     """
     if tex_compiler in {"latex", "pdflatex", "luatex", "lualatex"}:
-        commands = [
+        command = [
             tex_compiler,
             "-interaction=batchmode",
-            f'-output-format="{output_format[1:]}"',
+            f"-output-format={output_format[1:]}",
             "-halt-on-error",
-            f'-output-directory="{tex_dir.as_posix()}"',
-            f'"{tex_file.as_posix()}"',
-            ">",
-            os.devnull,
+            f"-output-directory={tex_dir.as_posix()}",
+            f"{tex_file.as_posix()}",
         ]
     elif tex_compiler == "xelatex":
         if output_format == ".xdv":
-            outflag = "-no-pdf"
+            outflag = ["-no-pdf"]
         elif output_format == ".pdf":
-            outflag = ""
+            outflag = []
         else:
             raise ValueError("xelatex output is either pdf or xdv")
-        commands = [
+        command = [
             "xelatex",
-            outflag,
+            *outflag,
             "-interaction=batchmode",
             "-halt-on-error",
-            f'-output-directory="{tex_dir.as_posix()}"',
-            f'"{tex_file.as_posix()}"',
-            ">",
-            os.devnull,
+            f"-output-directory={tex_dir.as_posix()}",
+            f"{tex_file.as_posix()}",
         ]
     else:
         raise ValueError(f"Tex compiler {tex_compiler} unknown.")
-    return " ".join(commands)
+    return command
 
 
 def insight_inputenc_error(matching):
@@ -200,14 +197,14 @@ def compile_tex(tex_file: Path, tex_compiler: str, output_format: str) -> Path:
     result = tex_file.with_suffix(output_format)
     tex_dir = config.get_dir("tex_dir")
     if not result.exists():
-        command = tex_compilation_command(
+        command = make_tex_compilation_command(
             tex_compiler,
             output_format,
             tex_file,
             tex_dir,
         )
-        exit_code = os.system(command)
-        if exit_code != 0:
+        cp = subprocess.run(command, stdout=subprocess.DEVNULL)
+        if cp.returncode != 0:
             log_file = tex_file.with_suffix(".log")
             print_all_tex_errors(log_file, tex_compiler, tex_file)
             raise ValueError(
@@ -237,18 +234,16 @@ def convert_to_svg(dvi_file: Path, extension: str, page: int = 1):
     """
     result = dvi_file.with_suffix(".svg")
     if not result.exists():
-        commands = [
+        command = [
             "dvisvgm",
-            "--pdf" if extension == ".pdf" else "",
-            "-p " + str(page),
-            f'"{dvi_file.as_posix()}"',
-            "-n",
-            "-v 0",
-            "-o " + f'"{result.as_posix()}"',
-            ">",
-            os.devnull,
+            *(["--pdf"] if extension == ".pdf" else []),
+            f"--page={page}",
+            "--no-fonts",
+            "--verbosity=0",
+            f"--output={result.as_posix()}",
+            f"{dvi_file.as_posix()}",
         ]
-        os.system(" ".join(commands))
+        subprocess.run(command, stdout=subprocess.DEVNULL)
 
     # if the file does not exist now, this means conversion failed
     if not result.exists():

scripts/make_and_open_docs.py

@@ -1,12 +1,12 @@
 from __future__ import annotations
 
-import os
+import subprocess
 import sys
 import webbrowser
 from pathlib import Path
 
-path_makefile = Path(__file__).parents[1] / "docs"
-os.system(f"cd {path_makefile} && make html")
+path_makefile = Path(__file__).resolve().parents[1] / "docs"
+subprocess.run(["make", "html"], cwd=path_makefile)
 
 website = (path_makefile / "build" / "html" / "index.html").absolute().as_uri()
 try:  # Allows you to pass a custom browser if you want.