command line compression?

Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 12:27 am

Is it possible to compress files (ex: make a folder a black hole archive) via command line? If yes how do I do it, and how do I extract it? My server drive is getting nearly full so I want to start archiving stuff. I'm hoping to be able to make black hole archives as they are 50% the original size which beats mostly all other compression methods but if that's not possible then anything will do.

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megaspaz · Post by **megaspaz** » Tue Jul 13, 2004 1:43 am

Red Squirrel wrote: Is it possible to compress files (ex: make a folder a black hole archive) via command line? If yes how do I do it, and how do I extract it? My server drive is getting nearly full so I want to start archiving stuff. I'm hoping to be able to make black hole archives as they are 50% the original size which beats mostly all other compression methods but if that's not possible then anything will do.

man tar

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wldkos · Post by **wldkos** » Tue Jul 13, 2004 3:33 am

a black hole???

+1 on the "man tar"

im sure well get questions on how to use it though, which is fine.

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 9:33 am

After second try I got it working but there's like hardly any compression on tars, so is there a different way? Black holes are incredible archives, you can get some folders down to like 10% the original size, depending on what's in it. Usually it's 50% but the few last folders I did locally I turned 1GB of data to like 50 megs lol... all logs and easy to compress files.

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megaspaz · Post by **megaspaz** » Tue Jul 13, 2004 2:24 pm

use the -j or -z options with tar. -j will use the bzip compression and -z will use the gzip compression.

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megaspaz · Post by **megaspaz** » Tue Jul 13, 2004 2:26 pm

does going from 71.3 MB down to 28.2 MB count as a black hole?

that's using the gzip compression on my home directory.

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 2:31 pm

Well that's pretty good I'll go with that then.

How to I fix this error though?

[root@localhost day_backup]# tar -cfz local.tar local.old
tar: local.tar: Cannot stat: No such file or directory
tar: Error exit delayed from previous errors
[root@localhost day_backup]#

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megaspaz · Post by **megaspaz** » Tue Jul 13, 2004 2:35 pm

the command structure matters when using tar.

tar -cvzf name_of_archive.tar.gz directory_or_files

because the z came in front of the f, you need to put the name of the tarball first before the source directory. it could also be an error in the naming convention in that you gave the -z option so it was expecting the output file to have a *.tar.gz extension.

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 4:08 pm

Thanks that worked... but I only got it down to 54MB and the folder was 64MB is that normal?

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megaspaz · Post by **megaspaz** » Tue Jul 13, 2004 4:13 pm

depends. i think gzip does really good on text files. if you got a lot of binaries, the compression might not be so good. if you want you can seperate out the commands. like do a tar first with no -z option and then use the gzip command.

man gzip

to get the options of gzip.

or you could try it with the -j option and try the bzip compression. iiirc, bzip should do better compression.

man bzip2

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 4:15 pm

It's mostly text file (html and php) there's some binaries such as pictures but most of it is html. I'll try it with other folders though and see what I get. If not I can just set my samba permissions to write and do it with power archiver. gzip is way faster then black hole at compressing though. If I want to black hole my whole backup folder It's something I'd leave on overnight.

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wldkos · Post by **wldkos** » Tue Jul 13, 2004 11:06 pm

Tar just makes an archive of the files with no compression. You need to add the -z for gzip compression which is really good. If you use -j in stead of -z you are using the bzip which is even better compression.

I think geekhaven had an article on this.

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 11:22 pm

Yeah while gzip and tar are good, they don't compete with black hole.

But it's ok, since it's good to know there's the tar command since I can use this to make quick archives. I have a 30GB folder on my server and I ain't black holing that over the network.

So I'll gzip that one, much faster.

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 13, 2004 11:25 pm

Hmm I just noticed I have backups of backups of backups at some places. while compression is good, nothing beats deletation, when you want to save space.

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Red Squirrel · Post by **Red Squirrel** » Wed Jul 14, 2004 1:17 am

hahaha I have an archive going and it's been like 2 hours.

It's a huge folder with tons of files of different type and sizes.

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