fix: prefer Git for Windows bash.exe when available on Windows

ahostbr · ahostbr · commit b521537bdc9c · 2026-05-17T17:48:14.000-04:00
Per @orhun's review on orhun#66: most users running terminal apps on Windows want a POSIX shell so the Ratatui demos behave the same as on Linux/macOS. The default-shell lookup now walks, in order: 1. `$SHELL` (already supported — useful when launching from Git Bash so the inherited shell is honoured). 2. Git for Windows `bash.exe` in well-known install locations: - `%ProgramW6432%\Git\{bin,usr/bin}\bash.exe` - `%ProgramFiles%\Git\{bin,usr/bin}\bash.exe` - `%ProgramFiles(x86)%\Git\{bin,usr/bin}\bash.exe` - `%LOCALAPPDATA%\Programs\Git\{bin,usr/bin}\bash.exe` 3. `bash.exe` anywhere on `PATH` (covers scoop / chocolatey installs). 4. `%COMSPEC%` (typically resolves to `cmd.exe`). 5. Literal `cmd.exe` as the final fallback. Verified on Windows 11 with Git for Windows installed at the default location — `bash.exe` is now the spawned PTY child: ProcessId : 204736 Name : bash.exe CommandLine : "C:\Program Files\Git/bin/bash.exe" Removing the Git install reverts to the `%COMSPEC%` / `cmd.exe` fallback verified by the previous commit.
diff --git a/src/runtime.rs b/src/runtime.rs
@@ -186,11 +186,17 @@ pub struct TerminalRuntime {
 
 /// Returns the default shell for the current platform.
 ///
-/// On Windows this prefers `%COMSPEC%` (the resolved command processor) and
-/// falls back to `cmd.exe`. On other platforms it falls back to `/bin/sh`.
+/// On Windows this prefers Git for Windows' `bash.exe` when it can be found
+/// (most users running terminal apps on Windows want a POSIX shell so the
+/// Ratatui demos behave the same as on Linux/macOS), then `%COMSPEC%` (the
+/// resolved command processor), and finally `cmd.exe`. On other platforms
+/// it falls back to `/bin/sh`.
 fn default_shell() -> String {
     #[cfg(windows)]
     {
+        if let Some(bash) = find_git_bash() {
+            return bash;
+        }
         env::var("COMSPEC").unwrap_or_else(|_| "cmd.exe".to_string())
     }
     #[cfg(not(windows))]
@@ -199,6 +205,54 @@ fn default_shell() -> String {
     }
 }
 
+/// Looks for a Git for Windows `bash.exe` in the well-known install
+/// locations, then on `PATH`. Returns the first match.
+#[cfg(windows)]
+fn find_git_bash() -> Option<String> {
+    use std::path::PathBuf;
+
+    // Standard Git for Windows install locations resolved via env vars so we
+    // honour installs on non-C: drives. `usr/bin/bash.exe` is the MSYS shell
+    // bundled with Git for Windows; `bin/bash.exe` is the shim used by the
+    // Git Bash launcher. Either is a fine PTY shell.
+    let env_bases = ["ProgramW6432", "ProgramFiles", "ProgramFiles(x86)"];
+    let install_subpaths = ["Git/bin/bash.exe", "Git/usr/bin/bash.exe"];
+
+    for env_var in env_bases {
+        let Ok(base) = env::var(env_var) else {
+            continue;
+        };
+        for sub in install_subpaths {
+            let candidate = PathBuf::from(&base).join(sub);
+            if candidate.is_file() {
+                return candidate.into_os_string().into_string().ok();
+            }
+        }
+    }
+
+    // Per-user install (Git for Windows scoop / user installer).
+    if let Ok(local_appdata) = env::var("LOCALAPPDATA") {
+        for sub in install_subpaths {
+            let candidate = PathBuf::from(&local_appdata).join("Programs").join(sub);
+            if candidate.is_file() {
+                return candidate.into_os_string().into_string().ok();
+            }
+        }
+    }
+
+    // Fall back to a `PATH` lookup so a custom install or `scoop shim` works.
+    if let Ok(path) = env::var("PATH") {
+        for entry in env::split_paths(&path) {
+            let candidate = entry.join("bash.exe");
+            if candidate.is_file() {
+                return candidate.into_os_string().into_string().ok();
+            }
+        }
+    }
+
+    None
+}
+
 impl TerminalRuntime {
     /// Spawns the shell PTY runtime.
     ///
