src/Pure/System/isabelle_platform.scala

   val ISABELLE_PLATFORM_FAMILY: String = {
     val family0 = get("ISABELLE_PLATFORM_FAMILY")
     if (family0 == "linux" && is_arm) "linux_arm" else family0
   }
 
-  def is_linux: Boolean =
-    ISABELLE_PLATFORM_FAMILY == "linux" ||
-    ISABELLE_PLATFORM_FAMILY == "linux_arm"
-  def is_macos: Boolean = ISABELLE_PLATFORM_FAMILY == "macos"
-  def is_windows: Boolean = ISABELLE_PLATFORM_FAMILY == "windows"
+  def is_linux: Boolean = ISABELLE_PLATFORM_FAMILY.startsWith("linux")
+  def is_macos: Boolean = ISABELLE_PLATFORM_FAMILY.startsWith("macos")
+  def is_windows: Boolean = ISABELLE_PLATFORM_FAMILY.startsWith("windows")
 
   def arch_64: String = if (is_arm) "arm64" else "x86_64"
   def arch_64_32: String = if (is_arm) "arm64_32" else "x86_64_32"
 
   def os_name: String = if (is_macos) "darwin" else ISABELLE_PLATFORM_FAMILY