How to unzip only the first few lines of a zip archive?

Question

I have a zipped text file a.zip I want to read the first 10 lines of it. Is it possible to do that without unzipping the whole file?

N0rbert · Accepted Answer · 2018-01-04 11:23:09Z

10

This simple pipe-script works for me:

zcat a.zip | head -n 10

Here:

answered Jan 4 '18 at 11:23

N0rbert

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this unzips the whole file. – yukashima huksay Jan 4 '18 at 11:41
5

@yukashima I'd guess it depends on the size of a.zip. When head terminates (after printing 10 lines) the zcat (which is gzip -dc behind the scenes) should receive a SIGPIPE and stop unzipping. – PerlDuck Jan 4 '18 at 11:53
@yukashimahuksay How do you know it unzips the whole file? I think all zip files keep the file list at the end of the archive, maybe it's just reading the whole file but not actually unzipping it – Xen2050 Jan 4 '18 at 12:38
I can confirm by example that it does not unzip the whole file as intended. zcat verybigfile.zip | head -10 prints the first 10 lines immediately. A full unzip would take ca. 10 minutes. – user27164 Aug 21 '20 at 14:55

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