fix: fix incompatibility with NixOS, where /bin/bash does not exist (#187)

* fix: fix incompatibility with NixOS, where /bin/bash does not exist

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

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

---------

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

Author: Atry

src/swerex/deployment/modal.py

@@ -214,7 +214,8 @@ async def start(
         t0 = time.time()
         token = self._get_token()
         self._sandbox = modal.Sandbox.create(
-            "/bin/bash",
+            "/usr/bin/env",
+            "bash",
             "-c",
             self._start_swerex_cmd(token),
             image=self._image,

src/swerex/runtime/local.py

@@ -99,7 +99,7 @@ def _strip_control_chars(s: str) -> str:
 def _check_bash_command(command: str) -> None:
     """Check if a bash command is valid. Raises BashIncorrectSyntaxError if it's not."""
     _unique_string = "SOUNIQUEEOF"
-    cmd = f"/bin/bash -n << '{_unique_string}'\n{command}\n{_unique_string}"
+    cmd = f"/usr/bin/env bash -n << '{_unique_string}'\n{command}\n{_unique_string}"
     result = subprocess.run(cmd, shell=True, capture_output=True)
     if result.returncode == 0:
         return
@@ -155,7 +155,7 @@ def _get_reset_commands(self) -> list[str]:
     async def start(self) -> CreateBashSessionResponse:
         """Spawn the session, source any startupfiles and set the PS1."""
         self._shell = pexpect.spawn(
-            "/bin/bash",
+            "/usr/bin/env bash",
             encoding="utf-8",
             codec_errors="backslashreplace",
             echo=False,

tests/test_execution.py

@@ -241,7 +241,9 @@ async def test_run_in_shell_bashlex_errors(runtime_with_default_session: RemoteR
 
 
 async def test_run_shell_check_exit_code(runtime_with_default_session: RemoteRuntime):
-    r = await runtime_with_default_session.run_in_session(A(command="/bin/bash -n <<'EOF'\necho 'hello world'\nEOF"))
+    r = await runtime_with_default_session.run_in_session(
+        A(command="/usr/bin/env bash -n <<'EOF'\necho 'hello world'\nEOF")
+    )
     assert r.exit_code == 0