Written by DrG the 7 Dec 09 at 08:17.

A smaller file size can be achieve with no additional software and not much difference in time.

Example : ( with nautilus and even with the weaker LZMA available by default in Karmic)
'gimp_2.6.1-1ubuntu3_i386.deb' is one of the deb packages of GIMP.
Size is 4.2 MB (4366488 bytes)

extract gimp_2.6.1-1ubuntu3_i386.deb
there will be three files in the resulting directory (3 items, totaling 4.2 MB)
1.control.tar.gz 8.1 KB (8272 bytes)
2.data.tar.gz 4.2 MB (4358024 bytes)
3.debian-binary 4 bytes (4 bytes)

Extract data.tar.gz there will be a directory named usr
Contents : 262 items, totalling 11.5 MB

Compress 'usr' with .tar.lzm
Size of resulting file 'usr.tar.lzma' is 2.7 MB (2800592 bytes)

delete contents otherthan control.tar.gz , debian-binary , and usr.tar.lzma
compress the folder
Resulting file 'gimp_2.6.1-1ubuntu3_i386.tar.lzma'

A smaller file size can be achieve with no additional software and not much difference in time. Example : ( with nautilus and even with the weaker LZMA available by default in Karmic) 'gimp_2.6.1-1ubuntu3_i386.deb' is one of the deb packages of GIMP. Size is 4.2 MB (4366488 bytes) extract gimp_2.6.1-1ubuntu3_i386.deb there will be three files in the resulting directory (3 items, totaling 4.2 MB) 1.control.tar.gz 8.1 KB (8272 bytes) 2.data.tar.gz 4.2 MB (4358024 bytes) 3.debian-binary 4 bytes (4 bytes) Extract data.tar.gz there will be a directory named usr Contents : 262 items, totalling 11.5 MB Compress 'usr' with .tar.lzm Size of resulting file 'usr.tar.lzma' is 2.7 MB (2800592 bytes) delete contents otherthan control.tar.gz , debian-binary , and usr.tar.lzma compress the folder Resulting file 'gimp_2.6.1-1ubuntu3_i386.tar.lzma' Size : 2.7 MB (2847218 bytes) ( difference in size is 1519270 bytes) Although now the file is not directly installable , there is 34.79 % decrease in size . The contents remains the same. There are other compression algorithms which can give a much better compression ratio .

Written by readmanr the 7 Dec 09 at 22:32.

xz is a file format and command line tool with syntax similar to that of gzip but uses LZMA2 instead of DEFLATE. As GNU Tar v1.22 has replaced the short option -J and reassigned it as a shortcut for --xz, there is no need to stay in the ice age by using lzma.
RPM in Fedora 12 has switched to using XZ compression, the XZ library is still in beta, but the file format has been finalized (instead of the not-finalized LZMA)

'gimp_2.6.1-1ubuntu3_i386.deb' 4.2M (4366488 bytes)
1.control.tar.gz (8272 bytes) 2.data.tar.gz (4358024 bytes) 3.debian-binary (4 bytes)

The the two .tar files compressed with .xz (.tar.xz, .txz) instead of .gz (.tar.gz, .tgz) the files are now...

1.control.tar.xz (7588 bytes) 2.data.tar.xz (2799000 bytes) 3.debian-binary (4 bytes)

Total size with .gz (4366300 bytes) 4.16M
Total size with .lzma (2847218 bytes) 2.71M
Total size with .xz (2806592 bytes) 2.67M
Total saving (.gz/.xz) of (1559708 bytes) 1.48M

This is an example of just one small file, the savings available by using a better compression are huge... in time, bandwidth, money, more space on the live CD for further apps.

xz is a file format and command line tool with syntax similar to that of gzip but uses LZMA2 instead of DEFLATE. As GNU Tar v1.22 has replaced the short option -J and reassigned it as a shortcut for --xz, there is no need to stay in the ice age by using lzma. RPM in Fedora 12 has switched to using XZ compression, the XZ library is still in beta, but the file format has been finalized (instead of the not-finalized LZMA) 'gimp_2.6.1-1ubuntu3_i386.deb' 4.2M (4366488 bytes) 1.control.tar.gz (8272 bytes) 2.data.tar.gz (4358024 bytes) 3.debian-binary (4 bytes) The the two .tar files compressed with .xz (.tar.xz, .txz) instead of .gz (.tar.gz, .tgz) the files are now... 1.control.tar.xz (7588 bytes) 2.data.tar.xz (2799000 bytes) 3.debian-binary (4 bytes) Total size with .gz (4366300 bytes) 4.16M Total size with .lzma (2847218 bytes) 2.71M Total size with .xz (2806592 bytes) 2.67M Total saving (.gz/.xz) of (1559708 bytes) 1.48M This is an example of just one small file, the savings available by using a better compression are huge... in time, bandwidth, money, more space on the live CD for further apps.

Written by DrG the 8 Dec 09 at 07:08.

If you need both compression and time you had to compile an external package FreeArc (combines multiple algorithms including lzma )
http://freearc.org/download/0.60RC/FreeArc-0.60RC2-linux-i386.tar.bz2 (for i386 )

With this , compress 'usr' folder with tar. > usr.tar
Then on command line , from the directory
arc a -m9 usr.tar.arc usr.tar
>> size : 2.4 MB (2476722 bytes) in 14.9 seconds(lzma took 20 seconds with -9 switch to make it 2.7 MB (2807429 bytes))
or
arc a -m3 usr.tar.arc usr.tar
>> size : 2.7 MB (2807627 bytes) in 3.37 sec

There are algorithms which gives much better compression but takes considerable time
Example: ( with the same file above )

Unpack 'data.tar.gz' to directory 'usr'
compress 'usr' with -6 option in paq8l ( available in karmic repo ) . For maximum compression , the swith is -8 but that much memory is not available in my system

If you need both compression and time you had to compile an external package FreeArc (combines multiple algorithms including lzma ) http://freearc.org/download/0.60RC/FreeArc-0.60RC2-linux-i386.tar.bz2 (for i386 ) With this , compress 'usr' folder with tar. > usr.tar Then on command line , from the directory arc a -m9 usr.tar.arc usr.tar >> size : 2.4 MB (2476722 bytes) in 14.9 seconds(lzma took 20 seconds with -9 switch to make it 2.7 MB (2807429 bytes)) or arc a -m3 usr.tar.arc usr.tar >> size : 2.7 MB (2807627 bytes) in 3.37 sec There are algorithms which gives much better compression but takes considerable time Example: ( with the same file above ) Unpack 'data.tar.gz' to directory 'usr' compress 'usr' with -6 option in paq8l ( available in karmic repo ) . For maximum compression , the swith is -8 but that much memory is not available in my system This will give 'usr.paq8l' Delete 'data.tar.gz' and directory 'usr' and compress the parent folder to 'gimp_2.6.1-1ubuntu3_i386.2.tar.lzma' size : 1.7 MB (1779197 bytes) (59.25 % reduction ) Now the bad side – The compression with paq8l took more than 30 min ( in Acer aspire 4720z ) The worse side – The decompression took around 30 min . This time will be much less in higher end PCs So not suitable for today's packages # !!!!!!!! Even with this much time taken , there can be a potential use of this paq8l – data transfer across slow Internet connections ( like 56k dial-up ) . Here the data received per second will be very small , this can be very efficiently handled by paq8l at runtime.( so no extra time will be taken ) # !!!!!!! There are other 'paq' s which gives some what similar compression within much less time but they are not available in repo. If interested , also look at - 1.http://www.squeezechart.com/record.html 2.http://www.maximumcompression.com/index.html 3.http://www.cs.fit.edu/~mmahoney/compression/