Xonfig: show sensitive env variables that could affect the shell behavior. (#5374)

* wip

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Added XONSH_SUBPROC_OUTPUT_FORMAT

---------

Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

news/xonfig_env.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Xonfig: show sensitive env variables that could affect the shell behavior.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

xonsh/xonfig.py

@@ -561,6 +561,21 @@ def _info(
     data.extend([("xontrib", xontribs_loaded())])
     data.extend([("RC file", XSH.rc_files)])
 
+    # Show sensitive env variables that could affect the shell behavior.
+    envs = {
+        "UPDATE_OS_ENVIRON": None,
+        "XONSH_CAPTURE_ALWAYS": None,
+        "XONSH_SUBPROC_OUTPUT_FORMAT": None,
+        "THREAD_SUBPROCS": None,
+        "ENABLE_ASYNC_PROMPT": True,
+        "ENABLE_COMMANDS_CACHE": False,
+        "XONSH_CACHE_EVERYTHING": True,
+        "XONSH_CACHE_SCRIPTS": None,
+    }
+    for e, show_if in envs.items():
+        if (val := XSH.env.get(e)) is not None and (show_if is None or val == show_if):
+            data.extend([(e, val)])
+
     formatter = _xonfig_format_json if to_json else _xonfig_format_human
     s = formatter(data)
     return s