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* We no longer use nix-populate standalone, rather we use it as a

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build action for `system' packages (like system.fix) that have
  dependencies on all packages we want to activate.

  So the command sequence to switch to a new activation configuration
  of the system would be:

    $ fix -i .../fixdescriptors/system.fix
    ...
    system.fix -> 89cf4713b37cc66989304abeb9ea189f

    $ nix-switch 89cf4713b37cc66989304abeb9ea189f

* A nix-profile.sh script that can be included in .bashrc.
This commit is contained in:
Eelco Dolstra 2003-04-09 12:26:48 +00:00
parent f56b7312b2
commit aa8fda4b54
8 changed files with 85 additions and 42 deletions
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scripts/nix-switch Executable file
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#! /usr/bin/perl -w
use strict;
my $hash = $ARGV[0];
$hash || die "no package hash specified";
my $prefix = $ENV{"NIX"} || "/nix"; # !!! use prefix
my $linkdir = "$prefix/var/nix/links";
# Build the specified package, and all its dependencies.
my $pkgdir = `nix getpkg $hash`;
if ($?) { die "`nix getpkg' failed"; }
chomp $pkgdir;
my $id = `nix info $hash | cut -c 34-`;
if ($?) { die "`nix info' failed"; }
chomp $id;
# Figure out a generation number.
my $nr = 0;
while (-e "$linkdir/$id-$nr") { $nr++; }
my $link = "$linkdir/$id-$nr";
print "$pkgdir\n";
# Create a symlink from $link to $pkgdir.
symlink($pkgdir, $link) or die "cannot create $link";
# Make $link the current generation by pointing $linkdir/current to
# it. The rename() system call is supposed to be essentially atomic
# on Unix. That is, if we have links `current -> X' and `new_current
# -> Y', and we rename new_current to current, a process accessing
# current will see X or Y, but never a file-not-found or other error
# condition. This is sufficient to atomically switch the current link
# tree.
my $current = "$linkdir/current";
print "switching $current to $link\n";
my $tmplink = "$linkdir/new_current";
symlink($link, $tmplink) or die "cannot create $tmplink";
rename($tmplink, $current) or die "cannot rename $tmplink";