From 745a2018147efd1bad16ec41bc7eaa55a1678dba Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Tue, 11 Dec 2012 13:14:17 +0100
Subject: [PATCH] Check whether /proc/sys/net/ipv6/conf/all/disable_ipv6 exists

---
 modules/tasks/network-interfaces.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/modules/tasks/network-interfaces.nix b/modules/tasks/network-interfaces.nix
index 412e62bfe80c..64cb4a6749eb 100644
--- a/modules/tasks/network-interfaces.nix
+++ b/modules/tasks/network-interfaces.nix
@@ -275,7 +275,9 @@ in
                 EOF
 
                 # Disable or enable IPv6.
-                echo ${if cfg.enableIPv6 then "0" else "1"} > /proc/sys/net/ipv6/conf/all/disable_ipv6
+                if [ -e /proc/sys/net/ipv6/conf/all/disable_ipv6 ]; then
+                  echo ${if cfg.enableIPv6 then "0" else "1"} > /proc/sys/net/ipv6/conf/all/disable_ipv6
+                fi
 
                 # Set the default gateway.
                 ${optionalString (cfg.defaultGateway != "") ''