From b9567aa8b6f935522d1037377e0e5205a7529fd8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Forsman?= <bjorn.forsman@gmail.com>
Date: Wed, 13 Feb 2019 11:28:28 +0100
Subject: [PATCH] install script: don't abort when "nix-channel --update" fails

Instead, print a message about what happened and tell the user what can
be done (run "[sudo -i] nix-channel --update nixpkgs" again at a later
time). This change allows installing Nix when you're offline.

Since the multi-user installer is so verbose, the message isn't printed
until the end.

Fixes issue #2650 ("installation without internet connection").
---
 scripts/install-multi-user.sh       | 10 +++++++++-
 scripts/install-nix-from-closure.sh |  5 ++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 6ee8dd485..3d2acaac8 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -240,10 +240,16 @@ EOF
 }
 trap finish_fail EXIT
 
+channel_update_failed=0
 function finish_success {
     finish_cleanup
 
     ok "Alright! We're done!"
+    if [ "x$channel_update_failed" = x1 ]; then
+        echo ""
+        echo "But fetching the nixpkgs channel failed. (Are you offline?)"
+        echo "To try again later, run \"sudo -i nix-channel --update nixpkgs\"."
+    fi
     cat <<EOF
 
 Before Nix will work in your existing shells, you'll need to close
@@ -737,7 +743,9 @@ setup_default_profile() {
     # otherwise it will be lost in environments where sudo doesn't pass
     # all the environment variables by default.
     _sudo "to update the default channel in the default profile" \
-          HOME="$ROOT_HOME" NIX_SSL_CERT_FILE="$NIX_SSL_CERT_FILE" "$NIX_INSTALLED_NIX/bin/nix-channel" --update nixpkgs
+          HOME="$ROOT_HOME" NIX_SSL_CERT_FILE="$NIX_SSL_CERT_FILE" "$NIX_INSTALLED_NIX/bin/nix-channel" --update nixpkgs \
+          || channel_update_failed=1
+
 }
 
 
diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index ab20774bb..62f7cb673 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -138,7 +138,10 @@ if ! $nix/bin/nix-channel --list | grep -q "^nixpkgs "; then
     $nix/bin/nix-channel --add https://nixos.org/channels/nixpkgs-unstable
 fi
 if [ -z "$_NIX_INSTALLER_TEST" ]; then
-    $nix/bin/nix-channel --update nixpkgs
+    if ! $nix/bin/nix-channel --update nixpkgs; then
+        echo "Fetching the nixpkgs channel failed. (Are you offline?)"
+        echo "To try again later, run \"nix-channel --update nixpkgs\"."
+    fi
 fi
 
 added=