cmd: unify unix-specific code

cmd/subscribe_unix.go

@@ -0,0 +1,18 @@
+// +build linux dragonfly freebsd netbsd openbsd
+
+package cmd
+
+const (
+	scriptExt                      = "sh"
+	scriptHeader                   = "#!/bin/sh\n"
+	clientCommandDescriptionSuffix = `The default config file for all client commands is /etc/ntfy/client.yml (if root user),
+or ~/.config/ntfy/client.yml for all other users.`
+)
+
+var (
+	scriptLauncher = []string{"sh", "-c"}
+)
+
+func defaultClientConfigFile() string {
+	return defaultClientConfigFileUnix()
+}