The bug was present in 1.6.3, but it seems to have been fixed in 1.6.3ubuntu0.1.
If you roll back to 1.6.3, it's easy to reproduce it: $ PAGER= $ apt changelog apt It shows this error message: usage: which [-as] program ... and then goes on to show the changelog for apt. Whether apt called which or not, it was a bug nonetheless. The changelog for apt doesn't mention fixing this, but it has been fixed because it cannot be reproduced on 1.6.3ubuntu0.1 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1782567 Title: apt changelog outputs "usage: which [-as] program ..." if variable PAGER doesn't exist Status in apt package in Ubuntu: Invalid Bug description: When variable PAGER isn't in the environment, apt changelog always outputs this message: usage: which [-as] program ... but it goes on and shows the changelog with less. Most certainly it's running: which $PAGER without checking first if PAGER is empty. sensible-browser has the same bug, but with variable BROWSER: bug #1782447 ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: apt 1.6.3 ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18 Uname: Linux 4.15.0-29-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.2 Architecture: amd64 CurrentDesktop: XFCE Date: Thu Jul 19 09:35:46 2018 InstallationDate: Installed on 2018-04-28 (81 days ago) InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) SourcePackage: apt UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1782567/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
