I have a question about finding the compression ratios of a zip (bzip2) file.I have written a procedure which upon certain criteria tar's and bzip2 certain directories and moves them to a near line storage.
Yesterday I happened to stumble upon it. The procedure has tared and bzipped 6 GB of data to 800MB. Is there any attribute in tar command which would yield a summary of the compression.Though I have gone through the man page of tar, I have not found anything affirmative.
In short: no.
tar doesn't compress anything, it's just an archiver, meaning it combines a list of files (including meta information like access times, permissions, ...) into one larger file. As a bonus it supports passing this file stream through a compression utility like gzip or bzip2. These 2 commands are completely equal, and the resulting files usually even have the same checksum:
One way to get the ratio would be by getting the sizes of the original and the compressed file with du, and feeding it to bc:
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openssl version -a
OpenSSL 0.9.7d 17 Mar 2004 (+ security fixes for: CVE-2005-2969 CVE-2006-2937 CVE-2006-2940 CVE2006-3738 CVE-2006-4339 CVE-2006-4343 CVE-2007-5135 CVE-2008-5077... (3 Replies)
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