Perl shows warnings when executing apt-cacher-cleanup.pl in forky:

$ dpkg -l | grep apt-cacher
ii  apt-cacher  1.7.33    all    Caching proxy server for Debian/Ubuntu/Devuan software repositories
$ dpkg -l | grep 'ii  perl '
ii  perl        5.42.2-3  amd64  Larry Wall's Practical Extraction and Report Language
$ su -
Password:
$ /usr/share/apt-cacher/apt-cacher-cleanup.pl
Possible precedence problem between ! and pattern match (m//) at /usr/share/apt-cacher/apt-cacher-cleanup.pl line 114.
Possible precedence problem between ! and pattern match (m//) at /usr/share/apt-cacher/apt-cacher-cleanup.pl line 114.
$ cat /usr/share/apt-cacher/apt-cacher-cleanup.pl
...
# change uid and gid if root and another user/group configured
if (($cfg->{user} && $cfg->{user} !~ 'root' && !$> )
    || ($cfg->{group} && $cfg->{group} !~ 'root' && !$) =~ /^0/)){
...

Maybe it should be something like
if (($cfg->{user} && $cfg->{user} !~ 'root' && !$> )
    || ($cfg->{group} && $cfg->{group} !~ 'root' && !($) =~ /^0/))){
or
    || ($cfg->{group} && $cfg->{group} !~ 'root' && $) !~ /^0/)){

Thanks for apt-cacher!

Chris

Chris,

Thanks for this. I think you (and the new perl operator precedence warning) have
uncovered a longstanding bug.

Does this patch fix it for you?

Mark

commit 897ed6969cce556ebe48c81996e2dafc10b4b189
Author: Mark Hindley <mark@hindley.org.uk>
Date:   Mon Aug 17 17:07:21 2026 +0100

    Fix spurious negation operator before $) variable.

    Longstanding bug exposed by new operator precedence warning in perl 5.42:

      Possible precedence problem between ! and pattern match (m//) at
      /usr/share/apt-cacher/apt-cacher-cleanup.pl line 114.

    $) is a space separated string of group numbers. Intended test is whether first
    group is 0, i.e. getegid() is root.

    Closes: #1143251

diff --git a/apt-cacher-cleanup.pl b/apt-cacher-cleanup.pl
index 3e229dd..cec7e71 100755
--- a/apt-cacher-cleanup.pl
+++ b/apt-cacher-cleanup.pl
@@ -111,7 +111,7 @@ check_install(); # Before we give up rights

 # change uid and gid if root and another user/group configured
 if (($cfg->{user} && $cfg->{user} !~ 'root' && !$> )
-    || ($cfg->{group} && $cfg->{group} !~ 'root' && !$) =~ /^0/)){
+    || ($cfg->{group} && $cfg->{group} !~ 'root' && $) =~ /^0/)){
     printmsg("Invoked as root, changing to $cfg->{user}:$cfg->{group} and re-execing.\n");
     setup_ownership($cfg);
     # Rexec to ensure /proc/self/fd ownerships correct which are needed for red

We believe that the bug you reported is fixed in the latest version of
apt-cacher, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1143251@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Mark Hindley <mark@hindley.org.uk> (supplier of updated apt-cacher package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Mon, 24 Aug 2026 15:35:01 +0100
Source: apt-cacher
Architecture: source
Version: 1.7.34
Distribution: unstable
Urgency: medium
Maintainer: Mark Hindley <mark@hindley.org.uk>
Changed-By: Mark Hindley <mark@hindley.org.uk>
Closes: 1143251
Changes:
 apt-cacher (1.7.34) unstable; urgency=medium
 .
   * Fix spurious negation operator before $) variable. (Closes: #1143251)
   * d/control: change to debhelper compat 14 and drop obsolete substvars.
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