Default cron PATH does not include /snap/bin

Status changed to 'Confirmed' because the bug affects multiple users.

I believe this will be fixed in v2.41 snapd.

This bug is old but I'm going to un-duplicate it. I don't believe it is fixed.

I've got a cron script on focal (cron 3.0pl1-136ubuntu1) which is indirectly running `lxc` from a snap (/snap/bin/lxc).

I found the following in mail though:

/home/ubuntu/autopkgtest/tools/autopkgtest-build-lxd: 139: lxc: not found
/home/ubuntu/autopkgtest/tools/autopkgtest-build-lxd: 1: lxc: not found

crontab(5) mentions the default as being "/usr/bin:/bin", and how it does NOT come from /etc/environment. What you have to do is set "PATH=/snap/bin:/usr/bin:/bin" at the top of the crontab file if you want to be able to use snaps. (You can't do "PATH=/snap/bin:$PATH"...)

pathnames.h has a #define for _PATH_DEFPATH where AFAICS this comes from. Maybe it's that which we would want to modify to fix this for cron in Ubuntu.

@laney i would agree to patch cron with our default path, with snap/bin included.

Status changed to 'Confirmed' because the bug affects multiple users.

Julian, thanks for the fix. In crontab(5) in cron 3.0pl1-136ubuntu2 the manpage
is now wrong. It says:

> Several environment variables are set up automatically by the cron(8) daemon.
> […] PATH is set to "/usr/bin:/bin". HOME, SHELL, and PATH may be overridden
> by settings in the crontab […]

and also

> On the Debian GNU/Linux system, cron supports the pam_env module, and loads
> the environment specified by /etc/environment and /etc/security/pam_env.conf.
> It also reads locale information from /etc/default/locale. However, the PAM
> settings do NOT override the settings described above nor any settings in the
> crontab file itself. Note in particular that if you want a PATH other than
> "/usr/bin:/bin", you will need to set it in the crontab file.

These should be fixed I think. There might be other spots that I didn't notice
yet too.

Secondly, as there are now tasks for stable releases, I think the SRU team
needs to be made aware of the implications of SRUing this change. It means that
the default PATH (if not overridden) will be different after applying the
update. There's a chance that users will then have different copies of
programs found resulting in their cron scripts potentially experiencing
behaviour changes. The benefits of consistency may outweigh the
risks/drawbacks of this behaviour change, but I think it should be considered
carefully when SRUing.

This bug was fixed in the package anacron - 2.3-30ubuntu2

---------------
anacron (2.3-30ubuntu2) hirsute; urgency=medium

  * Do not override PATH in anacrontab and cron.d anymore (LP: #1779767).
    - The latter change is needed because anacron when invoked by cron should
      inherit cron's PATH and not it's cron.d snippet.
    - This does not work on sysvinit, where it will now produce the wrong
      result because it inherits the init script's PATH variable, so it's
      not possible to forward to Debian

 -- Julian Andres Klode <email address hidden> Mon, 15 Mar 2021 16:58:18 +0100

This bug was fixed in the package cron - 3.0pl1-136ubuntu2

---------------
cron (3.0pl1-136ubuntu2) hirsute; urgency=medium

  * d/p/f/inherit-path.patch: Add -P option to inherit PATH from environment,
    thanks to Tom Jones for the patch (Closes: #688716)
  * Inherit PATH by default (LP: #1779767):
    - debian/crontab.main: Stop setting PATH
    - debian/cron.service, debian/cron.init: Pass -P to cron

 -- Julian Andres Klode <email address hidden> Mon, 15 Mar 2021 15:10:36 +0100

crontab(5) manpage being updated in LP: #1938924