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Appending a GZIP File


 
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# 1  
Old 11-09-2009
Appending a GZIP File

Guys,

I just want to know the difference in following (core difference)


zcat a.gz b.gz c.gz |gzip >d.gz

And

zcat a.gz >>d.gz
zcat b.gz >>d.gz
zcat c.gz >>d.gz


do we have 3 gzip header in 1st and only one in second case.
please let me know this in detail

Thanks,
M.Mohankumar.
# 2  
Old 11-09-2009
Hi,

As far as I know, your first command (zcat ... | gzip > d.gz) - 'cat's all the three compressed files - then compresses it, one after another and save it to a single file named d.gz.

In second case, you read a compressed file and append it to a file named d.gz. d.gz is NOT compressed. Adding a 'gz' to a file name does not compresses it.

Regards
# 3  
Old 11-09-2009
sorry ggs,

It is typo err

the actual second case is like

zcat a.gz |gzip >>d.gz
zcat b.gz |gzip >>d.gz
zcat c.gz |gzip >>d.gz


please let me know the exact diffenrence with gzip headers

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