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0
votes
1answer
32 views

What is the highest compression ratio compressor for pdf, djvu, and images

Comments so far have not been specific with the type of files they needed to compress and didn't reach a definitive answer I have a 1 TB hard drive full of pdf,djvu mostly and the rest are images and ...
3
votes
1answer
3k views

Clear unused space with zeros (btrfs)

How to clear unused space with zeros ? (I am asking for tool for btrfs filesystem) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like ...
0
votes
0answers
16 views

How do I create a deflate file suitable for HTTP?

Say I have index.html. How do I obtain index.html.deflate appropriate for serving through HTTP with the "deflate" encoding? I am coding a simple web server and I don't want to implement streaming ...
2
votes
1answer
2k views

Trying to compress avi file using ffmpeg

I used the command below to compress an avi file(using ubuntu) ffmpeg -i input.avi -vcodec msmpeg4v2 output.avi but I am getting these errors Incompatible sample format 's16' for codec 'ac3', ...
16
votes
2answers
17k 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 ...
19
votes
4answers
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?
4
votes
3answers
107 views

Compression / archiving that keeps permissions and file owner?

I know that similar questions have been asked about permissions, but which form of compression or archiving keeps the permissions and file owners of each file and directory? I was considering the ...
11
votes
3answers
590 views

What does the `-C` flag exactly do in `scp`?

I always use either rsync or scp in order to copy file from/to a remote machine. Recently, I discovered in the manual of scp (man scp) the flag -C -C Compression enable. Passes the -C flag to ...
0
votes
0answers
34 views

where to compress=lzo, btrfs with virtual disk images, with their vm's internally using btrfs

I've been using compress=lzo on my btrfs volumes, because I read this fast compression method actually increases drive performance. (Haven't tested myself.) I'm starting to use ...
1
vote
2answers
1k views

Mount compressed tar file and update it

How do I mount a .tar.gz file, update it (add new files, edit files), and then unmount it such that changes are reflected in the original compressed file? I'm open to other compression formats if no ...
3
votes
4answers
405 views

Is it possible to make a .tar.gz file directly from stdin? Or, I need to tar together already gzipped files

I'm going to tell you exactly what I need in order to clarify the cryptic question in the title. I'm currently making scheduled MySQL backups of all my databases with something like: mysqldump ... | ...
1
vote
1answer
51 views

How to reduce size of a FLAC file without damagind its quality?

I got collection of vinyls which I paid for them to be digitized in FLAC. However my Hard Drive is getting full (91% full as of today) and the smallest of these vinyls is 2.3 GB in size! I would ...
1
vote
2answers
256 views

How strong is the encryption of a zip file in Linux Mint

Zip encryption has had often a bad reputation of being weak, but some would argue that a zip file encrypted using certain algorithms (such as by using AES), together with strong password, is really ...
0
votes
1answer
63 views

Can I use lzma compression, without using “tar”, on OSX 10.10.3?

I kind of think of OSX as Unix by another name. But, if I need to move this to the Apple forum, please tell me! I can create tar files compressed using lzma as such: $ ls ./DbDumps alpha.dmp ...
6
votes
3answers
392 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 ...
0
votes
2answers
33 views

How to open compressed file in less mode [duplicate]

How do I open a compressed file in less mode. I am able to grep using zgrep and using zcatI can open, but the file is big I want to open in less mode.
7
votes
3answers
405 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 ...
0
votes
1answer
66 views

Compress multiple files and keep their name?

I have hundreds of .csv files that I need to compress into one file each. It should look like this originalname.csv.gz
1
vote
0answers
14 views

Pipe gzip output to Bluetooth transfer?

How do I pipe gzip output to Bluetooth transfer? I am able to send send file over Bluetooth using this command: bluetooth-sendto --device=12:23:35:96:45:45 file.tar However, piping gzip didn't ...
13
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 ...
2
votes
1answer
31 views

lrzip compression does not shrink random data

I'm trying to shrink down some big files around 3.0 GB each and I decided to use lrzip after seeing a few benchmarks and such however is it something I'm doing wrong or something as whenever I run ...
46
votes
6answers
31k 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. ...
32
votes
5answers
25k 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 ...
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?
2
votes
1answer
47 views

appendable and greppable archive on CentOS to hold many log files (logrotate on steroids)

I have a bunch of applications on a CentOS 6.3 box, which generate daily logs (text files with a very similar content) in this vein: /data/logs/app/my-2014-06-29.log ...
6
votes
1answer
497 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 ...
1
vote
2answers
251 views

Unzip error, is recovery possible?

I compressed 4 separate folders with some wedding videos (!!) a few months ago. Today I tried to unzip them, and had no problem with the last 2, but the first 2 of them show an error: ...
2
votes
1answer
452 views

cpio VS tar - what the best archive solution in order to compress hundred of directories to one file

I have hundreds of directories under /var/Recording, and each directory there will have subdirectories, including files, hard links and soft links. I want to compress all directories under ...
5
votes
3answers
1k 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 ...
8
votes
2answers
442 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 ...
5
votes
5answers
14k 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/ ...
1
vote
1answer
160 views

unpigz (and untar) to a specific directory

I know how to gunzip a file to a selected location. But when it comes to utilizing all CPU power, many consider pigz instead of gzip. So, the question is how do I unpigz (and untar) a *.tar.gz file ...
13
votes
6answers
12k 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. ...
8
votes
3answers
1k 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
2answers
386 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 ...
-1
votes
1answer
56 views

Erratic behavior with gzip on unix

I am compressing log files daily and very recently I have been seeing some crazy results on the file type of the file after compression. Normally you would expect file filename.gz returning gzip ...
1
vote
1answer
104 views

Handle compress command error messages on AIX

I am working on production issue and unable to reproduce error message for compress command. Current Solution We have case-esac block in shell wrapper that handles messages as follows; case "$MSG" ...
0
votes
2answers
240 views

Gzip file but excluding some directories|files and also append current date

I'm looking for a way to create a .tar.gz file from a directory but I have some doubts. I'm know that the command for create the file is: tar -zcvf /path/to/compressed/file.tar.gz /path/to/compress ...
2
votes
3answers
326 views

How to compress the directory and its contents

How do I compress a directory and its contents in ksh on AIX for a file I do compress filename
2
votes
0answers
75 views

How do I layer compression on top of encryption on top of BtrFS, per-file?

BtrFS should support this really, but it doesn't. So ECryptFS looks like it will fill the gap. The only thing is, how would I layer compression on top of this? Reasons for compression on top of ...
30
votes
1answer
52k 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 ...
8
votes
4answers
16k 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 ...
0
votes
0answers
73 views

Errors when installing Maldet on an Fedora 20 system, have had these before

I just installed maldetect-1.4.2 on a system(Fedora 20) and it gives this error when installing: gzip: stdin: unexpected end of file tar: Child returned status 1 tar: Error is not ...
12
votes
2answers
1k 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. ...
1
vote
1answer
55 views

Is there a difference between gunzip -c and gunzip in terms of system utilization?

Is there a difference between zcat/gunzip -c and gunzip apart from the obvious one that one outputs it to the terminal and the other decompresses it to a file? I'm looking from a CPU utilization ...
3
votes
2answers
240 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 ...
18
votes
4answers
25k 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 ...
0
votes
2answers
156 views

How to zip folder content on Ubuntu without keep the folder structure(path)

How can I compress a directory content without compress the full path folder structure too. I am using this command to zip a folder content under var/www/ directory, but when I unzip the ...
2
votes
1answer
101 views

Is there any size limit for the compress command?

Is there any particular size limit after which the compress command works? As I know for 0 byte file, the compress command does not work. But today I tried to compress a file of byte size 27 bytes ...
-2
votes
1answer
322 views

How to compress a single huge file (e.g. 200GB) file from command-line [closed]

I'd like to compress one huge file (~200GB) from the command line. no need for archiving its directory along with it, swift operation and high compression ratio preferred. What may be some good ways? ...