On Sat, 2016-06-04 at 11:17 +0200, Aurelien Jarno wrote: > On 2016-05-26 22:50, Ben Hutchings wrote: > > I'm inclined to add a check to linux-image prerm scripts that skips the > > question when DEBIAN_FRONTEND=noninteractive. > > > > Aside from that, I might add the check for a chroot or container, if > > there's a simple way to do that. > > You can use the command ischroot from the debianutils package.
Why would I want to add a dependency on that? It only solves half the
problem, anyway I ended up with:
# Are we in a container? Check for $container in pid 1's environment.
sub in_container {
my $res = 0;
if (my $fh = new FileHandle('/proc/1/environ', 'r')) {
local $/ = "\0";
$res = grep(/^container=/, <$fh>);
close($fh);
}
return $res;
}
# Are we in in a chroot? Compare root device and inode numbers with pid 1.
sub in_chroot {
my @my_root_st = stat('/');
my @pid1_root_st = stat('/proc/1/root');
return @my_root_st && @pid1_root_st &&
($my_root_st[0] != $pid1_root_st[0] || $my_root_st[1] !=
$pid1_root_st[1]);
}
But I'm preparing a rewrite of the maintainer scripts, not using Perl,
and the implementation as a shell script is even shorter:
# Are we in a container? Check for $container in pid 1's environment.
in_container() {
grep -qz '^container=' /proc/1/environ
}
# Are we in in a chroot? Compare root device and inode numbers with pid 1.
in_chroot() {
test "$(stat -L -c %d:%i /)" != "$(stat -L -c %d:%i /proc/1/root)"
}
Ben.
--
Ben Hutchings
The most exhausting thing in life is being insincere. - Anne Morrow
Lindberg
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