subshell.DetectShell should default to zsh on macOS.

.github/workflows/build.yml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       matrix:
         go-version:
-          - 1.23.7
+          - 1.23.8
         sys:
           - {os: ubuntu-latest}
           - {os: macos-13, shell: zsh}

go.mod

@@ -1,6 +1,6 @@
 module github.com/ActiveState/cli
 
-go 1.23.7
+go 1.23.8
 
 require (
 	github.com/99designs/gqlgen v0.17.54

internal/subshell/subshell.go

@@ -251,18 +251,27 @@ func detectShellParent() string {
 		multilog.Error("Failed to get parent process: %s", errs.JoinMessage(err))
 	}
 
+	shell := ""
 	for p != nil && p.Pid != 0 {
 		name, err := p.Name()
 		if err == nil {
 			if strings.Contains(name, string(filepath.Separator)) {
 				name = path.Base(name)
 			}
 			if supportedShellName(name) {
-				return name
+				if runtime.GOOS == "darwin" && name == bash.Name && shell == "" {
+					// The installer starts State Tool after installing it. The user typically invokes the
+					// installer using the one-line shell command. The one-liner tends to end up in bash,
+					// which is often not the user's default on macOS. Try looking one level up for the
+					// correct shell.
+					shell = name
+				} else {
+					return name
+				}
 			}
 		}
 		p, _ = p.Parent()
 	}
 
-	return ""
+	return shell
 }

internal/subshell/subshell_darwin.go

@@ -0,0 +1,34 @@
+//go:build darwin
+// +build darwin
+
+package subshell
+
+import (
+	"strings"
+
+	"github.com/ActiveState/cli/internal/subshell/bash"
+	"github.com/ActiveState/cli/internal/subshell/fish"
+	"github.com/ActiveState/cli/internal/subshell/tcsh"
+	"github.com/ActiveState/cli/internal/subshell/zsh"
+)
+
+var supportedShells = []SubShell{
+	&bash.SubShell{},
+	&zsh.SubShell{},
+	&tcsh.SubShell{},
+	&fish.SubShell{},
+}
+
+const (
+	SHELL_ENV_VAR = "SHELL"
+	OS_DEFAULT    = "zsh"
+)
+
+func supportedShellName(filename string) bool {
+	for _, subshell := range supportedShells {
+		if strings.EqualFold(filename, subshell.Shell()) {
+			return true
+		}
+	}
+	return false
+}

internal/subshell/subshell_lin_mac.go → internal/subshell/subshell_linux.go

@@ -1,5 +1,5 @@
-//go:build !windows
-// +build !windows
+//go:build linux
+// +build linux
 
 package subshell