use backup methods other than files and tapes. The -P argument is
a normal sh(1) pipeline with either $DUMP_VOLUME or $RESTORE_VOLUME
defined in the environment, respectively.
For example, I can back up my home to three DVD+R[W]s as so:
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/ad0s2e 40028550 10093140 26733126 27% /home
green# dump -0 -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /home
for gcc >= 2.5 and no-ops for gcc >= 2.6. Converted to use __dead2
or __pure2 where it wasn't already done, except in math.h where use
of __pure was mostly wrong.
