MKUZIP(8) MidnightBSD System Manager’s Manual MKUZIP(8)

NAME

mkuzip — compress disk image for use with geom_uzip(4) class

SYNOPSIS

mkuzip [−v] [−o outfile] [−s cluster_size] infile

DESCRIPTION

The mkuzip utility compresses a disk image file in such a way that the geom_uzip(4) class will be able to decompress resulting image in run-time. This allows for significant reduction of size of disk image at the expense of some CPU time required to decompress the data each time it is read. Internally, operation is done in two phases as follows:

1.

An infile image is split into clusters and each cluster compressed using zlib(3).

2.

Resulting set of compressed clusters along with headers allowing to independently locate each individual cluster is written into output file.

The options are:

−o outfile

Name the output file outfile. The default is to use the input name with the suffix .uzip.

−s cluster_size

Use cluster_size as the size of chunks the file being split up into. Default value is 16384 bytes. The cluster_size should be a multiple of 512 bytes.

−v

Display verbose messages.

NOTES

Compression ratio largely depends on the cluster size used. For large cluster sizes (16K and higher), typical compression ratios are only 1-2% less than those achieved with the gzip(1) utlity. However, it should be kept in mind that larger cluster sizes lead to higher overhead in the geom_uzip(4) class, as the class has to decompress the whole cluster even if only several bytes from that cluster have to be read.

The mkuzip inserts tiny shell script at the beginning of the generated image, which makes it possible to ‘‘run’’ the image just like any other shell script. This script tries to load geom_uzip(4) class if it is not loaded, configure image as an md(4) disk device using mdconfig(8) utility, and automatically mount it using mount_cd9660(8) utility to the mount point provided as a first argument.

EXIT STATUS

The mkuzip utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

gzip(1), zlib(3), geom(4), geom_uzip(4), md(4), mdconfig(8), mount_cd9660(8)

AUTHORS

Maxim Sobolev 〈sobomax@FreeBSD.org〉

MidnightBSD 0.3 September 10, 2004 MidnightBSD 0.3