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ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)


CentOS 2.1AS







xdelta − Invoke XDelta


xdelta subcommand [ option... ] [ operand... ]


XDelta provides the ability to generate deltas between a pair of files and later apply those deltas. It operates similar to the diff and patch commands, but works on binary files and does not produce a human readable output.

XDelta has two subcommands, delta and patch. Delta accepts two files and produces a delta, while patch accepts one original file and a delta and produces the other file. As opposed to the the diff(1) format, which can usually be reversed, these deltas are one way.

Each subcommand will be detailed seperately. In general, any input file may be compressed with gzip(1) and XDelta will automatically uncompress it into a temporary location before examining the file. This temporary location is either the value of the environment variable, if set, or "/tmp". Unless turned off, XDelta always verifies the integrity of reconstructed files with MD5 checksums. By default, XDelta compresses constructed deltas, but this feature may be turned off.

The delta subcommand has the following synopsis:

xdelta delta [ option... ] from to [ patch ]

Computes a delta from from to to and writes it to patch or the standard output if patch is omitted or is named "-".

The patch subcommand has the following synopsis:

xdelta patch [ option... ] patch [ from [ to ]]

Applies patch to from. If from was omitted, XDelta attempts to use the file with the original from file name. The from file must be identical to the one used to create the delta. Its MD5 checksum is used to verify this condition. The constructed file will be written to to unless to is named "-" or the original to file name if to is omitted.



Set the zlib compression level. Zero indicates no compression. Nine indicates maximum compression.


Print a short help message and exit.


Print the XDelta version number and exit.


Verbose. Prints a bit of extra information.


No verify. Turns off MD5 checksum verification of the input and output files.


Set an upper bound on the size of an in-memory page cache.


Author: Josh MacDonald
Manual Page Revision: 1.2; Release Date: Fri, 09 Apr 1999 15:25:54 -0700.
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