securetty - file which lists terminals from which root can log in
The file /etc/securetty contains the names of terminals (one per line,
without leading /dev/) which are considered secure for the transmission
of certain authentication tokens.
It is used by (some versions of) login(1) to restrict the
terminals on which root is allowed to login. See login.defs(5) if you
use the shadow suite.
On PAM enabled systems, it is used for the same purpose by
pam_securetty(8) to restrict the terminals on which empty passwords
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