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28
votes
5answers
23k 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 ...
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 ...
39
votes
7answers
27k 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. ...
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', ...
6
votes
2answers
2k 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
37 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
254 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
98 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
256 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 ...
4
votes
3answers
523 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
397 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 ...
4
votes
5answers
11k 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
56 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 ...
6
votes
6answers
2k 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
518 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
332 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
47 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
64 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
125 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
232 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
44 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 ...
22
votes
1answer
45k 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
14k 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
53 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
556 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
26 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 ...
1
vote
1answer
90 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 ...
3
votes
2answers
133 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 ...
16
votes
4answers
20k 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
95 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
70 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
178 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? ...
15
votes
5answers
13k 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 ...
3
votes
2answers
1k 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 ...
0
votes
0answers
16 views

Gzip Mutliple files using single command [duplicate]

Want to Gzip my all the .csv files into a gzip file. I am using this command. gzip *.csv; Problem File contains '//' in its name that's why command is giving error. Error : - '//File.csv' is not ...
0
votes
1answer
711 views

Private VPN compression for faster internet

Background: I'm a student, and currently the WiFi connection at my school is very slow (dead slow). I have an 8Gb 4G data-plan, but even with that, I'm running short at the end of the month. I have ...
0
votes
0answers
23 views

What does “GLib-CRITICAL” error mean? [duplicate]

I'm trying to working with complearn, I installed complearn- toolkits , gui etc. from terminal window. Now I'm trying ncd (normalized compression distance) code samples to find similarity distance ...
7
votes
3answers
777 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 ...
0
votes
1answer
43 views

Why scp with compression takes longer than without compression

I was playing around and noticed that secure-copying with compression takes longer than without compression time scp -C ./test.sql user@vmware:/home/user real 0m42.758s user 0m40.455s sys ...
2
votes
1answer
42 views

Is it possible and how to merge identical files between different snapshots in a btrfs file system?

I regularly use btrfs's snapshot to backup the whole system, but it's redundant to have identical files between different snapshots. Commonly, for example, I took a snapshot of @ as ...
1
vote
1answer
93 views

How to check if SSH compression is enabled?

I am experiencing severe slowdown in Git checkouts from VM. I've been told that one of the reasons may be SSH compression (either enabled or disabled). How to check that is the state of compression ...
2
votes
1answer
46 views

Compress a tar file without extracting the content

Is it possible to compress a tar file such that I don't end up with an archive file in an other archive file but just an archive file containing my content fx. a tar.gz file? I don't want to extract ...
2
votes
2answers
271 views

Estimate compressibility of file

Is there a quick and dirty way of estimating gzip-compressibility of a file without having to fully compress it with gzip? I could, in bash, do bc <<<"scale=2;$(gzip -c file | wc -c)/$(wc ...
2
votes
1answer
255 views

Zip does not compress files when zipping

I have zipped a file recursively in a directory. But what I notice with these last few zips is that the files do not get compressed. adding: ...
3
votes
2answers
81 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 ...
0
votes
2answers
98 views

Why don't the servers use 7z?

By default on a UNIX machine install, I can see the logs are rotated with gzip. Question: Why doesn't the UNIX world use by default 7z? It would be much more efficient than gzip.. I just compressed ...
2
votes
1answer
425 views

How to compress a TMPFS folder?

I'm looking for a way to compress a tmpfs folder on the fly. I would like to use it for a local cache folder with a lot of data. I know there is a way to use Redis with eg LZF compression, but I ...
2
votes
1answer
49 views

Disk usage inside archives, like ncdu

I am a fond user of the ncdu utility to figure out how space is used within a directory. However, I have a use case where I am trying to choose which folders to backup and which folders not to ...
5
votes
1answer
337 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 ...
2
votes
1answer
65 views

How can I tell when a file was compressed?

I want to find out when my log files were compressed by logrotate because when I received them from cron in my email, the logs came in as text in the main body of the email instead. I did: ls -1la ...