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* nix-switch now removes the link to the previously activated system 

package as a root of the garbage collector, unless `--keep' is
  specified.
This commit is contained in:
Eelco Dolstra 2003-04-24 11:43:11 +00:00
parent 24b3d0759e
commit 243370bc52
1 changed files with 20 additions and 2 deletions
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22
scripts/nix-switch
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@ -1,6 +1,14 @@
#! /usr/bin/perl -w
use strict;
my $keep = 0;
if (scalar @ARGV > 0 && $ARGV[0] eq "--keep") {
shift @ARGV;
$keep = 1;
}
my $hash = $ARGV[0];
$hash || die "no package hash specified";
@ -31,6 +39,12 @@ open HASH, "> $hashfile" or die "cannot create $hashfile";
print HASH "$hash\n";
close HASH;
my $current = "$linkdir/current";
# Read the current generation so that we can delete it (if --keep
# wasn't specified).
my $oldlink = readlink($current);
# 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
@ -39,10 +53,14 @@ close HASH;
# 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 $tmplink";
if (!$keep && defined $oldlink) {
print "deleting old $oldlink\n";
unlink $tmplink || print "cannot delete $tmplink";
unlink "$tmplink.hash" || print "cannot delete $tmplink.hash";
}