ZFD(7D) Devices ZFD(7D)


zfd - Zone file descriptor driver


The zfd character driver exports devices into the zone which can be used by
a a standalone process within the zone as stdin, stdout, and stderr. The
zfd driver behaves in a similar manner as the zcons(7D) device. Inside a
zone, the slave side devices appear as /dev/zfd/[0-4].

The zone's zfd device configuration is driven by zoneadmd and a zone
attribute zlog-mode which is somewhat of a misnomer since its purpose has
evolved. The attribute can have a variety of values, but the lowest two
positions in the value string are used to control how many zfd devices are
created inside the zone and if the primary stream is a tty.


With the t flag set, stdin, stdout, and stderr, are multiplexed onto a
single full-duplex stream which is configured as a tty. That is, ptem,
ldterm and ttycompat are autopushed onto the stream when the slave side is
opened. There is only a single zfd device (0) needed for the primary

When the n flag is set, it is assumed that output logging will be done
within the zone itself. In this configuration 1 or 2 additional zfd
devices, depending on tty mode (t flag), are created within the zone. An
application can then configure the zfd streams driver into a multiplexer.
Output from the stdout/stderr zfd(s) will be teed into the correspond
logging zfd(s) within the zone.


zlogin(1), zoneadmd(1M), zonecfg(1M), zcons(7D)

illumos October 16, 2015 illumos