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68

It comes down to a concept called entropy. See Wikipedia. The basic idea is that, if there existed a compression operation that could always make a file smaller, then logic dictates that said compression operation would be able to reduce any file to 0 bytes and still retain all the data. But this is absurd, because we know that 0 bytes can not convey any ...


58

If you're compressing things that are already compressed (AVI, JPEG, MP3), you won't gain much other than packing everything in a single file.


55

To exclude the bin and obj folders recursively you can use the command: 7z.exe a -t7z archive.7z FolderToArchive\ -mx0 -xr!bin -xr!obj


48

How exactly are you extracting the files? Are you using the command-line or the GUI? Are you dragging the files or selecting them and using the extract function? Are you using the shell-extension context-menu? If you enter a destination folder and then select the extract function or use the shell-extension, then they do not extract to a temporary folder ...


33

To install p7zip using Homebrew, first update your brew formulae to be sure you are getting the latest p7zip. $ brew update Use Homebrew to install p7zip: $ brew install p7zip Add all files in the sputnik directory to the compressed file heed.7z: $ 7z a heed.7z sputnik Unzip heed.7z: $ 7z x heed.7z


27

To exclude all .svn directories you need to add the -xr!?svn\* switch For example the following will create a backup of the C:\Project\To\Backup directory excluding any folders that satisfy ?svn: "C:\Program Files\7-Zip\7z.exe" a -r -tzip -y -xr!?svn\* Project.zip C:\Project\To\Backup\*


27

You can get 7zip on ubuntu by using following command: sudo apt-get install p7zip-full


25

Not really. A .tar.gz or .tgz file really is two formats: .tar is the archive, and .gz is the compression. So the first step decompresses, and the second step extracts the archive. To do it all in one step, you need the tar program. Cygwin includes this, as does GnuWin32. tar xzvf foobaz.tar.gz ; x = eXtract ; z = filter through gZip ; v = be Verbose ...


25

Compression works by looking for repetitive patterns inside the items to compress. Also because you do not want to lose any data while compressing your files, the compression must be lossless(*). Now with that in the back in your head, think about the way files (items) are stored on a computer. At the lowest level, they are all just a bunch of 0's and 1's. ...


25

From the 7-Zip Help file: a (Add) command Adds files to archive. Examples 7z a archive1.zip subdir\ adds all files and subfolders from folder subdir to archive archive1.zip. The filenames in archive will contain subdir\ prefix. 7z a archive2.zip .\subdir\* adds all files and subfolders from folder subdir to archive ...


24

There is a freeware Windows file splitter called HJSplit Available here. The website claims it can split files of any type and size, but 9GB is a big file.


19

7z x duane.zip -oduane Usage: 7z <command> [<switches>...] <archive_name> [<file_names>...] [<@listfiles...>] <Commands> ... x: eXtract files with full paths <Switches> ... -o{Directory}: set Output directory Edit: 7z x *.zip -o* extracts all *.zip archives to subfolders with names of these ...


18

There's nothing you can do in 7-Zip to prevent this. It is Chrome who downloads the file and opens it with its default application. At some point, Chrome was instructed to open ZIP files automatically after downloading. THis overrides the Ask where to save each file before downloading setting. There are at least three ways to revert this change: Open ...


17

Use the -v option (v is for volume) -v100m will split the archive into chunks of 100MB. 7z -v option supports b k m g (bytes, kilobytes, megabytes, gigabytes)


15

If you use Debian or Ubuntu it is in the standard repositories (http://packages.ubuntu.com/precise/p7zip) so you can install it with as little as aptitude install p7zip or for the full version that includes archive creation and other format support (http://packages.ubuntu.com/precise/p7zip-full): aptitude install p7zip-full There are no doubt packages ...


15

If you get the 7-Zip 9.13 beta you can change the archive type to LZMA2 and thus be able to use as many threads as you like, though the memory usage goes up phenomenally. Install the beta, right click the stuff you want to archive then under the 7-Zip contect menu click "Add to archive..." and you will get something similar to the window below. On the left ...


15

Legacy zip compression is akin to the Deflate method in 7-zip, and will offer the most compatibility between different compression software. From the Winzip KB: .Zip Legacy compression (maximum compatibility): The Legacy (Zip 2.0) compression option uses a traditional data compression algorithm, known as deflate, that is supported by all ...


15

Maybe you misunderstood what the author of that post meant. The vmlinuz file contains other things besides the gzipped content, so you need to find out where the gzipped content starts. To do that, use: od -A d -t x1 vmlinuz | grep '1f 8b 08 00' What this does is to show you where in that file you can find the gzip header. The output looks like: ...


14

There are a large variety of compression formats and methods available, some don't compress at all and are designed to store a number of files in one archive, and other newer experimental compressors (PAQ based) are designed to compress as aggressively as possible, regardless of the time it takes to perform said operation. You need to evaluate the features ...


14

You can do this from within the program itself. Simply launch the 7-Zip File Manager as Administrator (this is important), and then click on the Tools menu and select Options. Here you can set your file associations for many types, not just the .7z extension.


13

7-zip archives can be extracted with p7zip (http://p7zip.sourceforge.net/) on Linux. It is included in the repositories of: Debian, Fedora, Ubuntu and possibly other distributions too. List contents with (lower case L, for list): 7za l myarchive.7z Extract contents: 7za x myarchive.7z


13

When all else fails, read the FAQ: Why does drag-and-drop archive extraction from 7-Zip to Explorer use temp files? 7-Zip doesn't know folder path of drop target. Only Windows Explorer knows exact drop target. And Windows Explorer needs files (drag source) as decompressed files on disk. So 7-Zip extracts files from archive to temp folder and ...


13

Instead of using 7-Zip to exclude the .svn (or potentially _svn) folders, I would recommend using the svn export command (use svn.exe from SlikSVN) to export the working copy to a temporary folder: svn export C:\Path\To\WC C:\Backup\Staging Then use 7-Zip as follows: 7z.exe a "C:\Parth\To\Archive" "C:\Backup\Staging\*" -bd t7z -v2g -r Then delete the ...


12

The ZIP format doesn't allow for encrypting file lists. This means that file lists are viewable by anyone. Only the contents of the files is encrypted, which means that no-one can read the file without your password. Due to this, 7-zip only asks for your password before unzipping. If you need a format that encrypts the file list, use 7Z and make sure you ...


12

Just add > NUL: to the end of your command.


12

First you need to start 7-zip "as administrator" the first time you run it to assign the context-menu option. Otherwise 7-zip does not have the right to change anything. (I don't know why 7-zip does not do this during install when it already has admin-rights but i always need to do this after installing 7-zip) Then go to Extra / Options. In the first tab ...


11

Doh! I really should have looked harder for an answer. From the 7-Zip FAQ: Why does drag-and-drop archive extraction from 7-Zip to Explorer use temp files? 7-Zip doesn't know folder path of drop target. Only Windows Explorer knows exact drop target. And Windows Explorer needs files (drag source) as decompressed files on disk. So 7-Zip ...


11

Full details in the 7Zip help file, but something like this: 7z a archive.7z -p<strong password> -mhe -r -v4096m c:\path\to\stuff\* would probably get you started. "a" == "Add" command "p" == Encrypt with this password "mhe" == Encrypt headers and filenames. "r" == recurse source directories "v" == break archive into 4GB chunks for easy DVD burning ...


11

once you have 7zip installed, you can extract an archive like this: $ 7z x foo.7z



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