On Tue, Apr 19, 2016 at 09:42:11AM -0700, Nikolaus Rath wrote: > Your build system is missing /etc/mtab (should be a symlink to > /proc/mounts). > > At the moment I consider this a bug in your system, not in the > package. But I'm willing to be convinced by suitably convincing > references :-).
Ok. Let's try: * I think we can both agree that a package should be buildable both in "native" form but also in a chroot. * The file does not belong to any package: $ dpkg -S /etc/mtab dpkg-query: no path found matching pattern /etc/mtab * chroots are usually created by debootstrap. debootstrap does not create the symlink either. * schroot does not create the file when entering a chroot. * sbuild does not create the file when building a package. Based on the above, it seems that the file is only useful/required in living running systems at most, but not on chroots used to build packages. I found this documentation from Linux From Scratch: http://www.linuxfromscratch.org/lfs/view/development/chapter06/createfiles.html Historically, Linux maintains a list of the mounted file systems in the file /etc/mtab. Modern kernels maintain this list internally and exposes it to the user via the /proc filesystem. To satisfy utilities that expect the presence of /etc/mtab, create the following symbolic link: ln -sv /proc/self/mounts /etc/mtab The way I read that, it seems mtab is a leftover from the past and it's there only for "historical reasons", but it does not seem to be something which is actually required. Moreover, accesing mtab directly seems very "low level". The "mount" command shows the mounted filesystems (even if in a different format). But even this seems to be deprecated as well, this is what the mount manpage says about mount's "listing mode": The listing mode is maintained for backward compatibility only. For more robust and customizable output use findmnt(8), especially in your scripts. The findmnt command belongs to the mount package, which is "Essential: yes". So, to summarize: In a Debian chroot used to build packages, the symlink /etc/mtab may or may not be there (as this report itself shows). OTOH, in a Debian system the findmnt command is always there. Therefore, packages should probably not rely on /etc/mtab. If you still do not agree, please downgrade this bug, clone it, and reassign the cloned bug to sbuild, etc. Thanks.
