package usershell

import (

"os"

"os/exec"

"path/filepath"

"strings"

"golang.org/x/xerrors"

)

// Get returns the $SHELL environment variable.

func Get(username string) (string, error) {

// This command will output "UserShell: /bin/zsh" if successful, we

// can ignore the error since we have fallback behavior.

if !filepath.IsLocal(username) {

return "", xerrors.Errorf("username is nonlocal path: %s", username)

}

//nolint: gosec // input checked above

out, _ := exec.Command("dscl", ".", "-read", filepath.Join("/Users", username), "UserShell").Output()

s, ok := strings.CutPrefix(string(out), "UserShell: ")

if ok {

return strings.TrimSpace(s), nil

}

if s = os.Getenv("SHELL"); s != "" {

return s, nil

}

return "", xerrors.Errorf("shell for user %q not found via dscl or in $SHELL", username)

}