21655a70f5
Nix expressions.
To subscribe to a channel (needs to be done only once):
nix-channel --add \
http://catamaran.labs.cs.uu.nl/dist/nix/channels/nixpkgs-unstable
This just adds the given URL to ~/.nix-channels (which can also be
edited manually).
To update from all channels:
nix-channel --update
This fetches the latest expressions and pulls cache manifests. The
default Nix expression (~/.nix-defexpr) is made to point to the
conjunction of the expressions downloaded from all channels.
So to update all installed derivations in the current user
environment:
nix-channel --update
nix-env --upgrade '*'
If you are really courageous, you can put this in a cronjob or
something.
You can subscribe to multiple channels. It is not entirely clear
what happens when there are name clashes between derivations from
different channels. From nix-env/main.cc it appears that the one
with the lowest (highest?) hash will be used, which is pretty
meaningless.
116 lines
2.8 KiB
Plaintext
Executable file
116 lines
2.8 KiB
Plaintext
Executable file
#! @perl@ -w
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use strict;
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# Figure out the name of the `.nix-channels' file to use.
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my $home = $ENV{"HOME"};
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die '$HOME not set' unless defined $home;
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my $channelsList = "$home/.nix-channels";
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my @channels;
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# Reads the list of channels from the file $channelsList;
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sub readChannels {
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return if (!-f $channelsList);
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open CHANNELS, "<$channelsList" or die "cannot open `$channelsList'";
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while (<CHANNELS>) {
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chomp;
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push @channels, $_;
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}
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close CHANNELS;
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}
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# Writes the list of channels to the file $channelsList;
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sub writeChannels {
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open CHANNELS, ">$channelsList" or die "cannot open `$channelsList'";
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foreach my $url (@channels) {
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print CHANNELS "$url\n";
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}
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close CHANNELS;
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}
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# Adds a channel to the file $channelsList;
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sub addChannel {
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my $url = shift;
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readChannels;
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foreach my $url2 (@channels) {
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return if $url eq $url2;
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}
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push @channels, $url;
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writeChannels;
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}
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# Fetch Nix expressions and pull cache manifests from the subscribed
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# channels.
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sub update {
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readChannels;
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# Pull cache manifests.
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foreach my $url (@channels) {
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print "pulling cache manifest from `$url'\n";
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system "@bindir@/nix-pull '$url'/MANIFEST";
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die "cannot pull cache manifest from `$url'" if ($? != 0);
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}
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# Create a Nix expression that fetches and unpacks the channel Nix
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# expressions.
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my $nixExpr = "[";
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foreach my $url (@channels) {
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my $fullURL = "$url/nixexprs.tar.bz2";
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my $hash = `@bindir@/nix-prefetch-url '$fullURL' 2> /dev/null`
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or die "cannot fetch `$fullURL'";
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chomp $hash;
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# !!! escaping
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$nixExpr .= "((import @datadir@/nix/corepkgs/fetchurl) " .
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"{url = $fullURL; md5 = \"$hash\"; system = \"@system@\";}) "
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}
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$nixExpr .= "]";
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$nixExpr =
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"(import @datadir@/nix/corepkgs/channels/unpack.nix) " .
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"{inputs = $nixExpr; system = \"@system@\";}";
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# Instantiate and realise it.
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my $storeExpr = `echo '$nixExpr' | @bindir@/nix-instantiate -`
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or die "cannot instantiate Nix expression";
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chomp $storeExpr;
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my $outPath = `nix-store -qnfB '$storeExpr'`
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or die "cannot realise store expression";
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chomp $outPath;
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# Make it the default Nix expression for `nix-env'.
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system "@bindir@/nix-env --import '$outPath'";
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die "cannot pull set default Nix expression to `$outPath'" if ($? != 0);
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}
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while (scalar @ARGV) {
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my $arg = shift @ARGV;
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if ($arg eq "--add") {
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die "syntax: nix-channel --add URL" if (scalar @ARGV != 1);
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addChannel (shift @ARGV);
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last;
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}
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elsif ($arg eq "--update") {
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die "syntax: nix-channel --update" if (scalar @ARGV != 0);
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update;
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last;
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}
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else {
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die "unknown argument `$arg'";
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}
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}
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