If one cannot afford to buy extra disk space one can run the export and compress utilities simultaneously. This will prevent the need to get enough space for both the export file AND the compressed export file. Eg:
# Make a pipe
mknod expdat.dmp p # or mkfifo pipe
# Start compress sucking on the pipe in background
compress < expdat.dmp > expdat.dmp.Z &
# Wait a second or two before kicking off the export
sleep 5
# Start the export
exp scott/tiger file=expdat.dmp
Or export accross the network directly into the target database:
Host A:
mknod FIFO.dmp p
exp u/p FILE=FIFO.dmp rest_of_parameters…
Host B:
mknod FIFO2.dmp p
rsh host1 dd if=FIFO.dmp > FIFO2.dmp &
imp u/p FILE=FIFO2.dmp rest_of_parameters