General Questions • Re: dpkg question

check_merged_usr_via_aliased_dirs(){  local vendor  vendor=$(get_vendor)  case "$vendor" in  debian)    # In Debian some people have gotten so offended by the following _warning_    # that they have resorted to bullying and abuse. Life's too short, sorry.    return    ;;  ubuntu)    # Ubuntu does not seem interested in it.    return    ;;  esac  for d in /bin /sbin /lib /lib32 /libo32 /libx32 /lib64; do    linkname="$(readlink $DPKG_ROOT$d || true)"    if [ "$linkname" = "usr$d" ] || [ "$linkname" = "/usr$d" ]; then      warning "This system uses merged-usr-via-aliased-dirs, going behind dpkg's"      warning "back, breaking its core assumptions. This can cause silent file"      warning "overwrites and disappearances, and its general tools misbehavior."      warning "See <https://wiki.debian.org/Teams/Dpkg/FAQ#broken-usrmerge>."      break    fi  done}

Q: Does dpkg support merged-/usr-via-aliased-dirs?

A: No. This approach is considered broken by design and breaks many common expectations.

In dpkg the expected breakage includes:

failing to notice file conflicts with the subsequent silent file overwrites by f.ex. dpkg, dpkg-divert and update-alternatives,
files disappearing during package upgrades or diversion installation,
failing to activate triggers on pathnames,

failing to find pathnames on dpkg-query -S searches,
failing to install packages shipping the same filename in real and aliased directories (with rather cryptic errors), f.ex. to be able to install otherwise dependency satisfiable packages needed by old software,

completely messing up the filesystem by simply using dpkg-deb -x or tar -x.

If you have a system that has been installed recently (since Debian buster) or switched via the usrmerge hack, you might want to consider using the dpkg-fsys-usrunmess program (but beware that it should not be used in systemd's emergency mode) or reinstalling. For further information see Teams/Dpkg/MergedUsr.

$ apt show usrmerge
Package: usrmerge
Version: 35
Priority: optional
Section: admin
Maintainer: Marco d'Itri <md@linux.it>
Installed-Size: 38.9 kB
Provides: usr-is-merged
Depends: perl:any, libfile-find-rule-perl
Conflicts: acl (<< 2.2.52-3~), arptables (<< 0.0.4+snapshot20181021-1~), coreutils (<< 8.24-1~), cruft (<< 0.9.44~), cryptsetup (<< 2:1.7.0-1~), davfs2 (<< 1.5.2-1.2~), debianutils (<< 4.5~), ebtables (<< 2.0.10.4+snapshot20181205-1~), elvis-tiny (<< 1.4-24~), kbd (<< 2.0.4-4~), ksh (<< 93u+20120801-3.1~), less (<< 481-2~), libbrlapi-dev (<< 5.3.1-1~), libc0.1 (<< 2.35-4), libc0.3 (<< 2.35-4), libc6 (<< 2.35-4), libc6.1 (<< 2.35-4), libdm0-dev, libjson-c-dev (<< 0.12.1-1.1~), libpng12-0 (<< 1.2.54-6~), libusb-0.1-4 (<< 2:0.1.12-28~), mksh (<< 52b-1~), molly-guard (<< 0.7.1+exp1~), musl-dev (<< 1.1.9-1.1~), nano (<< 2.3.99pre3-1~), open-iscsi (<< 2.0.873+git0.3b4b4500-13~), open-vm-tools (<< 2:10.0.5-3227872-2~), policycoreutils (<< 2.4-4~), safe-rm (<< 0.12-6~), tcsh (<< 6.18.01-4~), vsearch (<< 1.9.5-2~), xfsdump (<< 3.1.6+nmu1~), xfslibs-dev (<< 4.9.0+nmu1~), yp-tools (<< 3.3-5~), zsh (<< 5.2-4~)
Breaks: cruft-ng (<< 0.4.4~), initramfs-tools (<< 0.121~)
Homepage: https://wiki.debian.org/UsrMerge
Tag: admin::filesystem, admin::install, implemented-in::perl,
interface::commandline, role::program, suite::debian, use::configuring
Download-Size: 12.5 kB
APT-Manual-Installed: no
APT-Sources: http://localhost:3142/debian bookworm/main amd64 Packages
Description: Convert the system to the merged /usr directories scheme
This package will automatically convert the system to the merged
/usr directory scheme, in which the /{bin,sbin,lib}/ directories are
symlinked to their counterparts in /usr/.
.
There is no automatic method to restore the precedent configuration, so
there is no going back once this package has been installed.

• https://wiki.debian.org/UsrMerge

$ ls -la /{bin,sbin,lib}lrwxrwxrwx 1 root root 7  6 Oct  2020 /bin -> usr/binlrwxrwxrwx 1 root root 7  6 Oct  2020 /lib -> usr/liblrwxrwxrwx 1 root root 8  6 Oct  2020 /sbin -> usr/sbin

dpkg_test_usermerge.sh.zip

Statistics: Posted by Aki — 2023-12-25 09:15