libnss-myhostname binary package in Ubuntu Mantic s390x

 This package contains a plugin for the Name Service Switch, providing host
 name resolution for the locally configured system hostname as returned by
 gethostname(2). It returns all locally configured public IP addresses or -- if
 none are configured, the IPv4 address 127.0.1.1 (which is on the local
 loopback) and the IPv6 address ::1 (which is the local host).
 .
 A lot of software relies on that the local host name is resolvable. This
 package provides an alternative to the fragile and error-prone manual editing
 of /etc/hosts.
 .
 Installing this package automatically adds myhostname to /etc/nsswitch.conf.

Source package