Ist auf diesem Mailinglisten-Eintrag nachzulesen.
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Zitat

Of course given 30 years to fester, this split made some interesting distro-
specific rules show up and go away again, such as "/tmp is cleared between
reboots but /usr/tmp isn't". (Of course on Ubuntu /usr/tmp doesn't exist and
on Gentoo /usr/tmp is a symlink to /var/tmp which now has the "not cleared
between reboots" rule. Yes all this predated tmpfs.

Danke m3
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