As stated, I have a bug concerning the $PATH variable. At first, I filed it against Yakuake, but it has everything to do with the shell, hence a post here.
Bug report : 428553 – Yakuake's path searching algorithm has issues
Summary : (I use opam, the OCaml package manager, but it has nothing special; any executable which can display two different versions should behave similarly)
$ opam --version # Current version of opam 2.0.7 $ sudo cp /home/me/.opam/common/lib/opam-devel/opam /usr/local/bin # Copy a beta version (2.1.0~beta3) to its advised location, in $PATH $ opam --version # Didn't register the new executable 2.0.7 $ which opam # Correctly searches in $PATH /usr/local/bin/opam $ /usr/local/bin/opam --version # The new executable 2.1.0~beta3 $ which opam -a /usr/local/bin/opam /usr/bin/opam $ /usr/bin/opam --version # The older version, still chosen by Yakuake 2.0.7 $ echo $PATH [local paths]:/usr/local/sbin:/usr/local/bin:/usr/bin:[more global paths] $ sudo mv /usr/bin/opam /tmp/me/opam $ opam --version bash: /usr/bin/opam: [No such file or folder / in French] $ which opam -a /usr/local/bin/opam