Questions tagged [compression]
Compression decreases the size of data.
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How to decompress a .bz2 file
I have a file as: filename.bz2 I need to decompress.
I have tried the command: tar xvjf filename.tar.bz2, but it didn't work as the file is not a tar file.
How do I decompress this file?
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How can I extract .rar files on the Mac?
How can I extract RAR files in macOS? The built-in Archive Utility only supports ZIP.
Is there anything else, built-in or third-party, that also supports RAR?
I don't mind whether it's Terminal-only ...
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How do I extract files from an MSI package?
We have some old patches that we want to get the files from but don't wish to spend the time installing them to a machine.
Can anyone advise a way to extract files from an MSI installation package?
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Why are tar.xz files 15x smaller when using Python's tar library compared to macOS tar?
Context
I'm compressing ~1.3 GB folders each filled with 1440 JSON files and find that there's a 15-fold difference between using the tar command and Python's built-in tarfile library on macOS or ...
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How to specify level of compression when using tar -zcvf?
I gzip directories very often at work. What I normally do is
tar -zcvf file.tar.gz /path/to/directory
Is there a way to specify the compression level here? I want to use the best compression ...
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Compress files from OS X terminal?
In the Finder, there is this wonderful ability to right click on a file or directory, select compress from the drop-down, and end up with a zipped file.
Is it possible to do the same thing from the ...
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How is PNG lossless given that it has a compression parameter?
PNG files are said to use lossless compression. However, whenever I am in an image editor, such as GIMP and try to save an image as a PNG file, it asks for the compression parameter, which ranges ...
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Pros and cons of bzip vs gzip?
I've known gzip for years, recently I saw bzip being used at work. Are they basically equivalent, or are there significant pros and cons to one of them over the other?
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Cannot decompress .tar.xz file, getting "xz: Cannot exec: No such file or directory" from tar
Per How do I uncompress a tarball that uses .xz?, I tried tar xf php-5.6.0RC4.tar.xz and tar -xJf php-5.6.0RC4.tar.xz and in both cases I get the following:
tar (child): xz: Cannot exec: No such file ...
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Creating an archive from a directory without the directory name being added to the archive
I have the following folder structure:
root
folder1
folder2
folder3
7za.exe
I want to run the 7-zip command line tool to compress all the files in folder1 to a zip file ...
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What are the best options to use when compressing files using 7 Zip?
I often have to gather log files and upload them to a central server (Owned by another company). The central server has a size limit of the file, so I am trying to create the smallest file possible ...
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Create a tar file for compressing files and directories on Mac OS X
I'm new to Mac OS X and am not sure how to do this:
I have three directories. I want to create a tar/zip file of them so that I can attach them to an email.
Any ideas?
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How to obtain maximum compression with .tar.gz? [duplicate]
The way i understand the use of tar + gzip is that tar is normally used to consolidate a grouping of files into a single file, then gzip is used to compress that file.
I recently learned that tar can ...
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Command to 'gzip' a folder?
I am new to Mac command prompt stuff. How do you create a gzip of a folder in Mac OS X? I was told by a few folks that if you want to create a gzip of a folder you should 'tar' it first and then 'gzip'...
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Compressing with RAR vs ZIP [closed]
A lot of people are compressing files with RAR, sending compressed files with RAR and so on.
ZIP is more standard and works on all platforms. Windows users have ZIP included and Linux users have no ...
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Compress and then encrypt, or vice-versa?
I am writing a VPN system which encrypts (AES256) its traffic across the net (Why write my own when there are 1,000,001 others already out there? Well, mine is a special one for a specific task that ...
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Can zipping a file break it?
I just asked someone to send me a zipped psd file.
They declined, citing that zipping a file can break the fonts.
I assumed zipping a file is perfectly reversible, hence why it is commonly used. I ...
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Different compression methods in 7zip: Which is best suited for what task?
So there are different compression methods in 7zip. Which method is best suited for what task?
For example: One difference between LZMA and LZMA2 is I can choose all my cpu cores, whereas in LZMA 2 ...
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How does NTFS compression affect performance?
I've heard that NTFS compression can reduce performance due to extra CPU usage, but I've read reports that it may actually increase performance because of reduced disk reads. How exactly does NTFS ...
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Compressing folders on a mac, without the .DS_Store
Is there anyway to get rid of the .DS_Store when compressing a folder on a mac?
I work on a mac and send work to clients in zip format, but always get questioned on the .DS_Store folder inside them. ...
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Optimize animated GIF size in command-line
How to compress GIF animations? For example by reducing the color index.
The files are generated using Imagemagick but optimization seems complicated.
For example, the following animation is 864KB ...
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Why does preset "veryfast" in FFmpeg generate the most compressed file compared to all other presets?
The FFmpeg wiki says that the best compression rate is by preset "veryslow".
But when I am trying it with my video then preset veryfast provides the best compression in my case.
The following is the ...
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What is the maximum compression ratio of gzip?
What is the largest size a gzip (say 10kb for the sake of an example) can be decompressed to?
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How does 'dictionary size' affect compression?
I know that higher size may lead to better compression ratio and vice verca. But is there a way I can decide better?.. since there are so many choices
So far I've noticed dictionary size ≈ file size ...
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.tar files without directory structure
I'm .taring some files with the path example/super_user/Output.*.
The resulting .tar looks like this:
+ example
+ super_user
- Output.zip
- Output.xml
- Output.txt
...
user36938
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Zip files without compression
I'd like to bundle a number of big files into a single file, to make them easier to share. The files are already compressed (eg. jpeg, video etc), so I don't need compression, only archiving. How can ...
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Is it possible to execute a file after extraction from a 7-Zip self-extracting archive (SFX) archive?
I'm try to make a compressed deploy-able application.
Currently I'm taking a set of files that I've published from my IDE (Visual Studio 2008 - WPF published application) and compressing ...
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How to make 7-Zip faster
I normally use WinRAR over 7-Zip simply because it's faster and only a little less efficient with compression. I did a few tests on different file types and sizes comparing the 7-Zip and WinRAR ...
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Is there a way to determine the decompressed size of a .bz2 file?
Is there a way to print the decompressed size of a .bz2 file without actually decompressing the entire thing?
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How to set password on already existing winrar archive and encrypt it also?
Not when creating new archive, but on existing archive. I would also like to know how to do that in other archiver.
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Extracting a tar.gz file returns, “This does not look like a tar archive.”
I have a tar.gz file and I want to extract it using terminal. I used following commands: tar tvzf ldtp_3.5.0.orig.tar.gz and tar -xvzf ldtp_3.5.0.orig.tar.gz. However, I get the same result for both ...
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How do I use 7-Zip CLI for Windows to create .tar.gz archives?
How can I use the 7-Zip CLI (7za.exe) on Windows to create .tgz archives, as I use tar zcvf archive.tgz source_files on Linux?
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How to do "Files to store without compression" in 7-zip?
Is there any way to selectively prevent certain file types from compression in 7-zip, like in WinRAR?
I'm trying to compress a huge folder (many gigabytes), and I don't want the already-compressed ...
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What is the cause of a high CPU usage of 'system and compressed memory' in Windows 10?
There is an observation to be made for Windows 10 on my laptop running with 24G memory available, and 2.5G used. There is no 'memory pressure'. Other questions have looked at memory consumption (...
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Why is a 7zipped file larger than the raw file? [duplicate]
Possible Duplicate:
Why doesn't ZIP Compression compress anything?
I tried 7zipping an .exe file but it actually became larger.
Is this the expected result?
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Can Double Zipping Cause Problems?
I have a directory that I have been storing a ton of files in. Among the 10ish types of files there are also .zips of other directories.
In my personal experience I vaguely remember issues when ...
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How can I achieve the best, standard ZIP compression?
I don't care how long it takes to compress, all I want to achieve is two things:
The absolute best possible compression ratio
Compatibility with standard readers, such as Windows and WinZip
So ...
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What if I checked the box "Compress this drive to save disk space" on an SSD?
I was wondering how it would effect an SSD if this was checked:
I was just curious whether it would save my SSD disk space?
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7-Zip seems unable to compress zero-filled virtual disk image after 1.8 GB
I am trying to compress a virtual disk image that is mostly empty. It has about 2 GB used out of 13.5, but even after zero filling the empty space, I am still only able to compress it to around ...
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Between xz, gzip, and bzip2, which compression algorithim is the most efficient?
Between xz, gzip, and bzip2, which compression algorithm gives the smallest file size and fastest speed when compressing fairly large tarballs?
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Why doesn't Gzip compression eliminate duplicate chunks of data?
I just did a little experiment where I created a tar archive with duplicate files to see if it would be compressed, to my awe, it was not! Details follow (results indented for reading pleasure):
$ dd ...
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Compressing many similar large images?
I'm dealing with a large archive of satellite images of the Earth, each one taken 15 minutes apart over the same area, therefore they are quite similar to each other. Two contiguous ones look like ...
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How to extract a gpg file
I have a file that is compressed. I used a program to find out what kind of file it is and it says that it's a gpg file. How do you uncompress a gpg file?
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What is the difference between rar and RAR5 compression?
What is the difference between rar and RAR5 compression ?
Which is better for which purpose vs the compression time.
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7-Zip compression on multi-core computers
Does 7-Zip take advantage of multiprocessor or multi-core systems when compressing?
For example, would there be a close to 16 times speed-up on a 16 core system assuming no disk or memory bottlenecks?...
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Is it possible to open a self-extracting compressed Windows file on a Mac?
If I have a compressed file that's stored as a self-extracting archive for Windows, i.e., a .exe file, is it possible to convert it to a zip file that can be unzipped under OS X? Alternatively, is ...
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Multithreaded support in 7za
(I posted this first on serverfault, but then I realized it probably belongs here.)
I'm trying compress a very large text file using 7za (p7zip) 9.20. The -mmt option doesn't seem to have any effect. ...
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FFMPEG / libx264: How to specify a variable frame rate but with a maximum?
Instead of providing a fixed frame rate to FFMPEG/libx264 (-r/-framerate), I would like to specify a variable frame rate with a MAXIMUM value, and allow libx264 to down the frame rate as it sees fit. ...
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How to unpack a chrome theme?
How to unpack a packed chrome theme(*.crx)? Their FAQ states how to pack, but not how to unpack.
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How can I evaluate the best choice of archive format for compressing files?
In general, I've observed the following:
Linux-y files or tools use bzip2 or gzip for distributing archives
Windows-y files or tools use ZIP for distributing archives
Many people use 7-Zip for ...
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