diff options
| -rw-r--r-- | doc/manual/command-ref/nix-channel.xml | 55 | ||||
| -rwxr-xr-x | scripts/nix-channel.in | 14 |
2 files changed, 68 insertions, 1 deletions
diff --git a/doc/manual/command-ref/nix-channel.xml b/doc/manual/command-ref/nix-channel.xml index 63ecba8f3eb7..c4cc04ce24d8 100644 --- a/doc/manual/command-ref/nix-channel.xml +++ b/doc/manual/command-ref/nix-channel.xml @@ -24,6 +24,7 @@ <arg choice='plain'><option>--remove</option> <replaceable>url</replaceable></arg> <arg choice='plain'><option>--list</option></arg> <arg choice='plain'><option>--update</option> <arg rep='repeat'><replaceable>names</replaceable></arg></arg> + <arg choice='plain'><option>--rollback</option> <arg choice='opt'><replaceable>generation</replaceable></arg></arg> </group> </cmdsynopsis> </refsynopsisdiv> @@ -80,6 +81,14 @@ condition="manual">See also <xref linkend="sec-channels" </varlistentry> + <varlistentry><term><option>--rollback</option> [<replaceable>generation</replaceable>]</term> + + <listitem><para>Reverts the previous call to <command>nix-channel + --update</command>. Optionally, you can specify a specific channel + generation number to restore.</para></listitem> + + </varlistentry> + </variablelist> </para> @@ -104,10 +113,54 @@ respectively.</para> <para>To subscribe to the Nixpkgs channel and install the GNU Hello package:</para> <screen> -$ nix-channel --add http://nixos.org/channels/nixpkgs-unstable +$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable $ nix-channel --update $ nix-env -iA nixpkgs.hello</screen> +<para>You can revert channel updates using <option>--rollback</option>:</para> + +<screen> +$ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.nixpkgsVersion' +"14.04.527.0e935f1" + +$ nix-channel --rollback +switching from generation 483 to 482 + +$ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.nixpkgsVersion' +"14.04.526.dbadfad" +</screen> + +</refsection> + +<refsection><title>Files</title> + +<variablelist> + + <varlistentry><term><filename>/nix/var/nix/profiles/<replaceable>username</replaceable>/channels</filename></term> + + <listitem><para><command>nix-channel</command> uses a + <command>nix-env</command> profile to keep track of previous + versions of the subscribed channels. Every time you run + <command>nix-channel --update</command>, a new channel generation + (that is, a symlink to the channel Nix expressions in the Nix store) + is created. This enables <command>nix-channel --rollback</command> + to revert to previous versions.</para></listitem> + + </varlistentry> + + <varlistentry><term><filename>~/.nix-defexpr/channels</filename></term> + + <listitem><para>This is a symlink to + <filename>/nix/var/nix/profiles/<replaceable>username</replaceable>/channels</filename>. It + ensures that <command>nix-env</command> can find your channels. In + a multi-user installation, you may also have + <filename>~/.nix-defexpr/channels_root</filename>, which links to + the channels of the root user.</para></listitem> + + </varlistentry> + +</variablelist> + </refsection> </refentry> diff --git a/scripts/nix-channel.in b/scripts/nix-channel.in index 8e07821c43c7..b8c93df18c32 100755 --- a/scripts/nix-channel.in +++ b/scripts/nix-channel.in @@ -199,6 +199,20 @@ while (scalar @ARGV) { last; } + elsif ($arg eq "--rollback") { + die "$0: ‘--rollback’ has at most one argument\n" if scalar @ARGV > 1; + my $generation = shift @ARGV; + my @args = ("$Nix::Config::binDir/nix-env", "--profile", $profile); + if (defined $generation) { + die "invalid channel generation number ‘$generation’" unless $generation =~ /^[0-9]+$/; + push @args, "--switch-generation", $generation; + } else { + push @args, "--rollback"; + } + system(@args) == 0 or exit 1; + last; + } + elsif ($arg eq "--help") { exec "man nix-channel" or die; } |