[Bug 1792004] Re: built-in PATH seems to have sbin and bin out of order; and inconsistent

[Julian Andres Klode]

APT sets "/usr/sbin:/usr/bin:/sbin:/bin" as its PATH since disco. We
explicitly do not add /snap/bin to the path as discussed internally,
because we do not want deb maintainer scripts to be affected implicitly
by snaps (they can still specify /snap/bin/<name>).

** Changed in: apt (Ubuntu)
       Status: New => Fix Released

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Title:
  built-in PATH seems to have sbin and bin out of order; and
  inconsistent

Status in apt package in Ubuntu:
  Fix Released
Status in bash package in Ubuntu:
  Fix Released
Status in busybox package in Ubuntu:
  New
Status in dash package in Ubuntu:
  New
Status in dpkg package in Ubuntu:
  Won't Fix
Status in pam package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  New
Status in bash package in Debian:
  New

Bug description:
  [Impact]

   * For consistency reasons sbin should be ordered before bin in PATH.

  [Test Case]

   * $ env -u PATH /bin/bash -c 'echo $PATH'

  And check that matching pairs in PATH, have /sbin variant leading /bin
  variant.

  [Regression Potential]

   * Ubuntu does not ship duplicate binries, with different behaviour
  between /sbin and /bin, thus all binaries will continue to be found in
  all locations. Also PATH is normally already set in the environment,
  and this change only affects the fallback path when bash is executed
  without any environment, i.e. booting with 'init=/bin/bash'

  [Other Info]
   
   * Original bug report detailing inconsistent paths between various shells.

  ---

  
  $ env -u PATH /bin/sh -c 'echo $PATH'
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

  $ env -u PATH /bin/dash -c 'echo $PATH'
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

  $ systemd-run --unit test-env env # ... and check journal for PATH
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

  $ env -u PATH /bin/bash -c 'echo $PATH'
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.

  $ env -u PATH /bin/busybox sh -c 'echo $PATH'
  /sbin:/usr/sbin:/bin:/usr/bin

  $ grep 'export PATH=' -r initramfs-tools-0.131ubuntu10/
  initramfs-tools-0.131ubuntu10/mkinitramfs:export PATH='/usr/bin:/sbin:/bin'
  initramfs-tools-0.131ubuntu10/init:export PATH=/sbin:/usr/sbin:/bin:/usr/bin

  dracut.sh has DRACUT_PATH=${DRACUT_PATH:-/sbin /bin /usr/sbin /usr/bin} exported as PATH
  dracut-047+31/modules.d/99shutdown/shutdown.sh:export PATH=/usr/sbin:/usr/bin:/sbin:/bin

  $ cat /etc/environment
  PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"

  apt & dpkg => should probably initiate /usr/local-less PATH

  Imho the rest should probably be harmonised to:

  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin

  ===

  From a duplicate
  https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1614080 :

  $ for i in 12.04 12.10 13.04 13.10 14.04 14.10 15.04 15.10 16.04; do echo $i; docker run -it --rm ubuntu:$i bash -c "unset PATH; /bin/bash -c 'echo \$PATH'"; done
  12.04
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  12.10
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  13.04
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  13.10
  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  14.04
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
  14.10
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
  15.04
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
  15.10
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
  16.04
  /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.

  I believe later releases of bash, do too include CWD in the built-in
  PATH.

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