Windows 7-Zip Chunks, Linux Un-chunk My Heart

Written by James McDonald

May 31, 2017

Chunking Files with 7-Zip on Windows

From windows you can do the whole shebang directions here ==> http://www.techulator.com/resources/6601-How-split-join-files-using-7-zip-free-tool.aspx

This is my directions for chunking something on windows and then combining the chunks on Linux

On Windows you can compress and split a big file into smaller chunks using 7-Zip. This is especially good if you need to transfer them across an internet link and don’t want one massive monolithic transfer.

In Windows. Right click on the file and choose 7-Zip => Add to archive…

Then from the Add to Archive dialog box select the chunk size by either entering a value or select a predefined chunk size in the “Split to Volumes, bytes” field

So this nicely creates a series of files the size you specify

ls -1 *.7z.*
bigfile20170524.7z.001
bigfile20170524.7z.002
bigfile20170524.7z.003
bigfile20170524.7z.004
bigfile20170524.7z.005
bigfile20170524.7z.006
bigfile20170524.7z.007
bigfile20170524.7z.008
bigfile20170524.7z.009
bigfile20170524.7z.010
bigfile20170524.7z.011
bigfile20170524.7z.012
bigfile20170524.7z.013
bigfile20170524.7z.014
bigfile20170524.7z.015
bigfile20170524.7z.016
bigfile20170524.7z.017
bigfile20170524.7z.018
bigfile20170524.7z.019
bigfile20170524.7z.020
bigfile20170524.7z.021

However sometimes you have to move them to Linux and then recombine them but how to do it.

When 7-Zip breaks things into chunks the first chunk has the 7-Zip header information and then the remainder are just archive data:

root@ubuntu1:/pst/pst# file bigfile20170524.7z.001 
bigfile20170524.7z.001: 7-zip archive data, version 0.3
root@ubuntu1:/pst/pst# file bigfile20170524.7z.002 
bigfile20170524.7z.002: data
root@ubuntu1:/pst/pst# file bigfile20170524.7z.003
bigfile20170524.7z.003: data
root@ubuntu1:/pst/pst# file bigfile20170524.7z.004
bigfile20170524.7z.004: data
root@ubuntu1:/pst/pst# file bigfile20170524.7z.005
bigfile20170524.7z.005: data
... etc ...

 

So what you need to do is join file1 + file2 + file3 and output to a new file. To do that in Linux you can just use cat as follows.

The Important Bit is Here

unchunk 7-zip chunks

cat *.7z.* >> bigfile20170524.7zAnd then from there you can then use the normal command line 7-Zip to extract the files from the archive

# install 7-Zip 
root@ubuntu1:/pst/pst# apt-get install p7zip-full
# extract the file or files from the archive with the x switch
root@ubuntu1:/pst/pst# 7z x bigfile20170524.pst.7z 

7-Zip [64] 9.20  Copyright (c) 1999-2010 Igor Pavlov  2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,4 CPUs)

Processing archive: bigfile20170524.pst.7z

 

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