pax

pax(1) is a POSIX 1003.2 conformant replacement for tar and cpio that handles most UNIX archive and tape formats. pax uses the vdelta algorithm to construct efficient delta archives that contain bytewise changes from a given base archive. gzip and compress archives are also handled on input and output.

To create a vdelta compressed base archive: 

     tw | pax -w -f base -z -
To create a delta archive on the base above (record file changes only): 
     tw | pax -w -f delta -z base
To read the delta archive: 
     pax -r -f delta -z base
To create a delta archive from linux-1.2.0 to linux-1.2.5: 
     pax -rf linux-1.2.5.tar.gz -wf 0-5.pax.gz \
     	-x gzip -z linux-1.2.0.tar.gz
To create the linux-1.2.5 archive: 
     pax -rf 0-5.pax.gz -z linux-1.2.0.tar.gz \
     	-wf linux-1.2.5.tar.gz -x tar -x gzip
The bax script, shipped with pax, combines tw and pax for handy backup control.

Glenn Fowler
Information and Software Systems Research
AT&T Labs Research
Florham Park NJ
September 16, 1999