using python to unpack selected files from 7zip archives using subprocess

Question

I am currently using subprocess to unpack a selection or zip files using 7zip. I have to use this unpacking method instead of the zipfile module because on occasion the zipfile corrupts shapefiles. My current method is:

try:

    for file in os.listdir(downloads):
        print file
        expression2 = sevenzip + " e " +downloads + '\\' + file + " -oC:\Users\Oulton"
        print expression2

    #os.system(r"C:\Users\Oulton\7z e C:\Users\Oulton\install.zip -oC:\Users\Oulton")
        subprocess.call(expression2)



except:
        time.sleep(3)
        traceback.print_exc()

But this is not convenient because:

I only want to unpack certain .shp files and not all of the other junk in each zip
A shell is opened and closed for each iteration, I would prefer the shell to stay open throughout
I have to use manual input to overwrite duplicately named files using this method

"On occasion the zipfile [module] corrupts shapefiles"? Is this really the case? It seems that `zipfile` is exactly what you want -- I'd recheck this conclusion. Or see if there's a bugfix available if it really is an issue in Python. — Managu, Feb 03 '12 at 15:29
Are you on Windows? If so, are you reading/writing files in binary mode? [This](http://stackoverflow.com/questions/7082454/zipfile-python-module-bytesize-difference) question might be relevant. — Managu, Feb 03 '12 at 15:30
@Managu thanks for the tip however yes even when writing binary certain shapefiles have become corrupted strangely - I repeated the process several times and it was always the same shapefiles being corrupted, which are unpacked without incident using cmd 7z — Alex Oulton, Feb 03 '12 at 15:38

Uku Loskit · Accepted Answer · 2012-02-03T16:43:40.660

1

7z e C:\Users\Oulton\install.zip -oC:\Users\Oulton" *.shp -r
Use Windows's for loops to reuse the same shell: http://www.robvanderwoude.com/for.php

3.

-ao (Overwrite mode) switch
Specifies the overwrite mode during extraction, to overwrite files already present on disk.

-i and -x can be used to respectively include or exclude specific files for extraction.

7z e C:\Users\Oulton\install.zip -oC:\Users\Oulton -ir!*.shp -ir!*.mxd -ir!*.shx -ir!*.sbn -ir!*.dbf -ir!*.xml

edited Feb 03 '12 at 16:43

answered Feb 03 '12 at 15:34

Uku Loskit

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thanks that helps, ask for extracting just certain specific files from each zip can you give any insight? – Alex Oulton Feb 03 '12 at 15:49
do you know file names and directory structure? – Uku Loskit Feb 03 '12 at 15:55
yes I only want to extract files ending in [.shp .mxd .shx .sbn .dbf .xml] – Alex Oulton Feb 03 '12 at 16:13

using python to unpack selected files from 7zip archives using subprocess

1 Answers1