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Diffstat (limited to 'usr.bin/mkuzip/mkuzip.8')
-rw-r--r-- | usr.bin/mkuzip/mkuzip.8 | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/usr.bin/mkuzip/mkuzip.8 b/usr.bin/mkuzip/mkuzip.8 new file mode 100644 index 0000000..277faf2 --- /dev/null +++ b/usr.bin/mkuzip/mkuzip.8 @@ -0,0 +1,84 @@ +.\" ---------------------------------------------------------------------------- +.\" "THE BEER-WARE LICENSE" (Revision 42): +.\" <sobomax@FreeBSD.ORG> wrote this file. As long as you retain this notice you +.\" can do whatever you want with this stuff. If we meet some day, and you think +.\" this stuff is worth it, you can buy me a beer in return. Maxim Sobolev +.\" ---------------------------------------------------------------------------- +.\" +.\" $FreeBSD$ +.\" +.Dd July 29, 2001 +.Dt MDGZIP 8 +.Os +.Sh NAME +.Nm mkuzip +.Nd compress a +.Xr geom_uzip 4 +image +.Sh SYNOPSIS +.Nm +.Op Fl v +.Op Fl o Ar outfile +.Op Fl s Ar cluster_size +.Ar infile +.Sh DESCRIPTION +The +.Nm +utility compresses a disk image file in such a way that the +.Xr geom_uzip 4 +class will be able to decompress resulting image in run-time +when it loaded into memory. This allows for significant reduction +of memory footprint of memory-based filesystem 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: +.Bl -enum +.It +An +.Ar infile +image is split into clusters and each cluster compressed using +.Xr zlib 3 . +.It +Resulting set of clusters along with headers allowing to +independently locate each individual cluster is written into +output file. +.El +.Pp +The options are: +.Bl -tag -width Fl +.It Fl o Ar outfile +Name the output file +.Ar outfile . +The default is to use the input name with the suffix +.Sq .uzip . +.It Fl s Ar cluster_size +Use +.Ar cluster_size +as the size of chunks the file being split up into. Default value +is 16K. The +.Ar cluster_size +should be multiple of block size of the +.Xr geom_uzip 4 +device (usually 512 bytes). +.It Fl v +Display verbose messages. +.El +.Sh NOTES +Compression ratio largely depends on the cluster size used. For +large cluster sizes of (16K and higher) typical compression ratios +are only 1-2% less than those achieved with the +.Xr gzip 1 +utlity. However, it should be kept in mind that larger cluster +sizes lead to higher overhead in the +.Xr geom_uzip 4 +class, as the class has to decompress the whole cluster even if +literally only several bytes from that cluster have to be read. +.Sh SEE ALSO +.Xr gzip 1 , +.Xr zlib 3 , +.Xr geom_uzip 4 , +.Xr boot 8 , +.Xr loader 8 +.Sh DIAGNOSTICS +Exit status is 0 on success and >0 on error. +.Sh AUTHORS +.An Maxim Sobolev Aq sobomax@FreeBSD.org . |