compress/decompress don't take you back to the same file Post: 302283195

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Top Forums UNIX for Dummies Questions & Answers compress/decompress don't take you back to the same file Post 302283195 by chebarbudo on Monday 2nd of February 2009 09:10:55 PM

02-02-2009

Registered User

Thanks Lakris,
You are right. I knew very few about tars before I had this problem.
So I explored in details the content of the archives using

Code:

tar -tvf system.tgz > system.lst
tar -tvf system.01.tgz > system.01.lst
diff system.lst system.01.lst

1) Path, attributes and size are strictly identical before and after decompression/recompression.

2) Dates can be different:
- regular files, block and character devices, hard links and named pipes always keep the same date
- symbolic links never keep the same date. Actually they get the current time of decompression.
- I was not able to build any theory about directories

3) Owners are different in some cases. I assume that only UID/GID is kept for the owner. So if the archive comes from another system (which is my case), UID/GID can result in a different username/groupname.

If anyone has serious knowledge about tars, can he/she confirm what I said?
Can this explain the difference between the original archive and the one resulting of a decompression/recompression?

Thanks for your help
Santiago

chebarbudo

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dist::zilla::app::command::build

Dist::Zilla::App::Command::build(3pm)			User Contributed Perl Documentation		     Dist::Zilla::App::Command::build(3pm)

NAME

       Dist::Zilla::App::Command::build - build your dist

VERSION

       version 4.300020

SYNOPSIS

	 dzil build [ --trial ] [ --tgz | --no-tgz ] [ --in /path/to/build/dir ]

DESCRIPTION

       This command is a very thin layer over the Dist::Zilla "build" method, which does all the things required to build your distribution.  By
       default, it will also archive your distribution and leave you with a complete, ready-to-release distribution tarball.

EXAMPLE

	 $ dzil build
	 $ dzil build --no-tgz
	 $ dzil build --in /path/to/build/dir

OPTIONS

   --trial
       This will build a trial distribution.  Among other things, it will generally mean that the built tarball's basename ends in -TRIAL.

   --tgz | --no-tgz
       Builds a .tar.gz in your project directory after building the distribution.

       --tgz behaviour is by default, use --no-tgz to disable building an archive.

   --in
       Specifies the directory into which the distribution should be built.  If necessary, the directory will be created.  An archive will not be
       created.

AUTHOR

       Ricardo SIGNES <rjbs@cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Ricardo SIGNES.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.14.2							    2012-06-21				     Dist::Zilla::App::Command::build(3pm)