I am looking to take dd disk images of some small disk volumes and compres= s the dd output in stream rather than after the fact. Is that possible? My experiments so far seem to indicate that it needs to be a two step process.= I'd prefer that it be one step, but I've not succeeded in getting it to work with pipes.
With most systems you don't need dd for disks, just for tapes. For unix I/O to tapes it is one read/write per tape block, so dd is often used to reblock data. tar will write block of a specified size, but most other programs don't. tar cf - . | dd of=/dev/tape obs=32k tar cf - . | gzip | dd of=/dev/tape obs=32k to compress a raw disk to a disk file, dd if=/dev/disk ibs=32k | gzip > outfile but I think you can also just do gzip < /dev/disk > outfile You only need dd if you need reblocking, either as input or output. If you want to write the result to tape, gzip < /dev/disk | dd of=/dev/tape obs=32k or dd if=/dev/disk ibs=32k | gzip | dd of=/dev/tape obs=32k Disk I/O is normally buffered by the system automatically, but it may be faster and/or more efficient to use a large block size with dd. dd without an if will read stdin, without of will write stdout. gzip without any parameters will compress stdin and write stdout. -- glen ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
