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41
votes
6answers
28k views

How to XZ a directory with TAR using maximum compression?

So I need to compress a directory with max compression. How can I do it with xz? I mean I will need tar too because I can't compress a directory with only xz. Is there a oneliner to produce e.g. ...
38
votes
1answer
2k views

What happened to bzip1?

bzip2 had been a de facto standard for quite strong compression throughout many years already. I myself had typed the bzip2 command thousands of times already, which makes me wonder - what happened to ...
30
votes
5answers
24k views

Is it possible to mount a gzip compressed dd image on the fly?

I like create an image backup for the first time I'm backing up a system. After this first time I use rsync to do incremental backups. My usual image backup is as follows: Mount and zero out the ...
23
votes
4answers
21k views

Clear unused space with zeros (ext3,ext4)

How to clear unused space with zeros ? (ext3,ext4) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like FSArchiver is looking for "used space" ...
23
votes
1answer
47k views

How can I reduce a video's size with ffmpeg?

How can I use ffmpeg to reduce the size of a video by lowering the quality (as minimally as possible, naturally, but I need it to run on a mobile device that doesn't have much available space)? I ...
18
votes
3answers
4k views

Does tar actually compress files, or just group them together?

I usually assumed that tar was a compression utility, but I am unsure, does it actually compress files, or is it just like an ISO file, a file to hold files?
17
votes
4answers
22k views

How to uncompress zlib data in UNIX?

I have created zlib-compressed data in Python, like this: import zlib s = '...' z = zlib.compress(s) with open('/tmp/data', 'w') as f: f.write(z) (or one-liner in shell: echo -n '...' | python2 ...
17
votes
5answers
15k views

Which file compression software for linux offers the highest size reduction? [closed]

I do a ton of file compression. Most of the stuff I am compressing is just code, so I need to use loss less compression. I was wondering if there was anything that offers a better size reduction ...
14
votes
1answer
15k views

Zip everything in current directory

I'd like to compress and package everything, including files and folders in current directory, into a single ZIP file on Ubuntu. What would be the most convenient command for this (and name of the ...
12
votes
8answers
3k views

Memory problems when compressing and transferring a large number of small files (1TB in total)

I have 5 million files which take up about 1TB of storage space. I need to transfer these files to a third party. What's the best way to do this? I have tried reducing the size using .tar.gz, but ...
12
votes
2answers
727 views

Fastest way of working out uncompressed size of large GZIPPED file

Once a file is gzipped, is there a way of quickly querying it to say what the uncompressed file size is (without decompressing it), especially in cases where the uncompressed file is > 4GB in size. ...
10
votes
2answers
6k views

How to create a tar.gz file from a folder excluding a folder

How do I exclude a file or folder while creating a tar.gz file with tar command?
10
votes
2answers
5k views

How can I view gzipped files in less without having to type zless?

I am using Ubuntu, and I would like to be able to type less compressed_text_file.gz and page the contents of the text file in uncompressed form. Is there a way to do this?
10
votes
3answers
1k views

Universal extractors

With an increasing number of archive/compression file formats, is there a single free/open-source command line tool to rule them all? Perhaps something with a consistent / unified set of flags? (note ...
8
votes
4answers
15k views

Is it possible to compress a very large file (~30 GB) using gzip?

Is it possible to compress a very large file (~30 GB) using gzip? If so, what commands, switches, and options should I use? Or is there another program (preferably one commonly available on Ubuntu ...
8
votes
2answers
421 views

Create a gzip file of a predetermined size

I want to test an upload of files of content type application/x-gzip of various sizes ranging from 100 MB to 999 MB. How can go I about creating .gz files of these predetermined sizes? If I do dd ...
8
votes
3answers
612 views

How do I compress files in-place?

I have a machine with 90% hard-disk usage. I want to compress its 500+ log files into a smaller new file. However, the hard disk is too small to keep both the original files and the compressed ones. ...
7
votes
6answers
212 views

Is there any program to provide a consistent interface across multiple archive types?

At the moment, if I download a compressed file, it could be any of a .tar.gz archive, a tar.bz2 arhive, a .zip archive or a .gz archive. And each time I do so, I have to remember what the command line ...
7
votes
3answers
350 views

Can tarring files improve compression?

Can tarring a bunch of files together improve compression with the standard tools, e.g. gzip, bzip2, xz? I've long thought this to be the case but never tested it out. If we have 2 copies of the same ...
7
votes
2answers
351 views

How to store a large folder in a single file without compression

Sorry if this is a stupid question, but I want to take a 78gb folder and store it in a single file (for upload into a cloud service), as if I am compressing it in an archive, but I don't want any ...
7
votes
6answers
5k views

How do I grep recursively through .gz files?

I am using a script to regularly download my gmail messages that compresses the raw .eml into .gz files. The script creates a folder for each day, and then compresses every message into its own file. ...
7
votes
3answers
797 views

How to recompress 2 million gzip files without storing them twice?

I have about 2 million (60GiB) of gzipped small files and I would like to create a compressed archive containing all of them in an uncompressed version. Unfortunately, I cannot just uncompress them ...
6
votes
2answers
3k views

What's the difference between tar.gz and tar.Z?

The downloads on this page, e.g. of NetCDF C/C++/Fortran 4.1.3, show tar.Z and tar.gz formats. The tar.Z doesn't even have a configure file in it. What is it used for?
6
votes
3answers
344 views

Does gz compression ratio improve over time?

I have some process that creates a stream of millions of highly similar lines. I'm piping this to gz. Does the compression ratio improve over time in such a setup? I.e. is the compression ratio better ...
6
votes
2answers
1k views

Why use cpio for initramfs?

I am making my own initramfs following the Gentoo wiki. Instead of the familiar tar and gzip, the page is telling me to use cpio and gzip. Wikipedia says that cpio is used by the 2.6 kernel's ...
6
votes
1answer
339 views

How should I combine many compressed files into one archive?

I have a few hundred .tar.xz files which are almost identical (they are daily database dumps, and the database changes slowly). I believe that due to the similarities in the uncompressed files, they ...
6
votes
1answer
233 views

How to specify additional parameters for GNU sort's --compress-program option?

sort --compress-program=/bin/gzip works fine, but how can I pass options down to the compression programm (e.g. --best or --fast)? sort --compress-program=/bin/gzip\ --best failes with the error ...
6
votes
1answer
3k views

On the Fly Compression for a Directory

I have a directory that is always going to be storing text files that are rarely (think weekly) used. Naturally this is a great place to use compression. However, rather than having to use tar ever ...
5
votes
3answers
2k views

Is there a command to list the compressed file sizes for files within a .zip file?

I'd like to see the absolute size in bytes of each file that has been compressed into single zip file. Having read the zip man page, I'm not sure that that utility can do it. This is on Mac OS X. ...
5
votes
3answers
829 views

Unpack file compressed in .txz and .tar with one command

I have a file compressed in *.txz. After unpacking it I received a *.tar file. Is there any way to unpack it twice with one command? I mean unpack file (*.tar).txz with one command? For know I'm do ...
5
votes
3answers
8k views

speed up gzip compression

Is it possible to speed up the gzip process? I'm using mysqldump "$database_name" | gzip > $BACKUP_DIR/$database_name.sql.gz to backup a database into a directory, $BACKUP_DIR. the manpage ...
5
votes
1answer
5k views

How to extract files from uImage?

Buildroot is generating Images for an embedded device where they should run on. This is working very well. In those Images the rootfs is included. Due to some research I'd like to look into that ...
5
votes
1answer
814 views

Appending checksum information to file

I'd like to embed checksum information into file, that I transfer. It's tar.gz or tar.xz file and I can only transfer one file to remote side. How do you recommend I embed checksum information? I ...
5
votes
2answers
2k views

rsync-like tool that supports compression and maintains hardlinks?

I use an rsync-based backup scheme to maintain daily (and soon weekly and monthly as well) "snapshots" of my file server, using rsync's link-dest feature to store hardlinks between the snapshots for ...
5
votes
2answers
608 views

Best compression of similar files?

I've got a few full old backups of things like binary database dumps. Obviously, they don't differ much so doing full backups is not the smartest idea here. For now, I'm looking for a compression ...
5
votes
1answer
5k views

What's the difference between gunzip and unzip?

What is the difference between gunzip and unzip? Tried to search but couldn't find anything relevant with this.
5
votes
1answer
354 views

Command-line incremental backup tools

Which command line backup tool(s) has the best compression ratio? I want to backup my entire system, including media files, text files etc. I found this list on the Arch wiki site but I don't know ...
5
votes
1answer
395 views

Is there any way in BTRFS to set compression permanently?

I have a USB HDD. I want to mount it with compression enabled. I can do in the fstab of my system or even using udev rules. The problem is that I won't mount my USB HDD on my computer only. Up to ...
4
votes
5answers
12k views

How to read a .war file?

I am trying to view the content of a .war file. I first did set its permissions with chmod 777 then when I try to accces it using: cd /usr/local/standalone/deployments/Sample.war/WEB-INF/classes/ ...
4
votes
1answer
1k views

Does ssh compress connections in a tunnel individually?

I have one compressed SSH tunnel with one tunnel and multiple connections over it. Data in every connection tunneled is rather homogeneous, but compressing an interleaved stream will obviously make ...
3
votes
8answers
3k views

Triple compression and I only save 1% in space?

I've been trying to save space on my linux server, and I had a folder containting, in subfolders, 22GB of images. So I decided to compress them. First I used tar: tar -zcf folder.tar folder Then ...
3
votes
4answers
338 views

Is there a way to redirect a file that is written

I have an application which I can not change, that writes to a big 250 GB plain text file. After compressing with GZ it is only 30 GB. This application has no option of compressing it's output, and ...
3
votes
2answers
811 views

Compressed filesystem inside a file in Linux

I have a flash drive which is FAT32 formatted. I want to put a linux filesystem on the drive inside a file. I know I can do this by creating a file and formatting is with ext3 (or any other file ...
3
votes
2answers
3k views

What Linux utility can split a large file into a multi-file archive that can be opened on Windows?

I have a 6GB file which I need to transport on DVDs. I have a Linux system, while the recipient has a Windows system. Is there any way for me to make a multi-part archive to spread the file across two ...
3
votes
2answers
86 views

In what situation would a tarball (.tgz) be almost the same size as the original

I just tarballed a dump of some websites (configs, image directory, css directory, and site content (html files etc)) using tar czf sitedump.tgz backup_folder/. The original "backup_folder" was about ...
3
votes
2answers
2k views

Making tar split archives as it compresses?

I want to compress a file with tar but I'd like to know if its possible to do it while splitting the files. I know that in windows is possible to do this with winrar, I also know I can use split but ...
3
votes
3answers
703 views

Different count for compressed file listing vs directory listing

I was taking a backup of a folder, where I used the following command : sudo tar -zcvf www.tar.gz /var/www/ It successfully compressed, just for verifying the number of files in the compressed ...
3
votes
2answers
171 views

Tell gzip/bzip2/7z/etc not to compress already-compressed files?

I'm tarring up /home, and piping it through bzip2. However, I've got lots of already-compressed files out there (.jpg, .mp4, .mkv, .webm, etc) which bzip2 shouldn't try to compress. Are there any ...
3
votes
1answer
4k views

How to make nemo support compressing files by context menu?

I use Cinnamon on ArchLinux and Nemo is it's default file manager. I've tried 3 GUI file archivers (p7zip with WxGTK, peazip & file-roller), but none of them add a "compress option" in the context ...
3
votes
1answer
2k views

initramfs image compression other than gzip

can the initramfs image be compressed by a method other than gzip, such as lzma?