Shrinking (compressing) and restoring (decompressing) of data.

learn more… | top users | synonyms

2
votes
1answer
1k views

I want to understand Buildroot - the 3 compression config options (kernel, initramfs & rootfs)

I'm using buildroot to generate my images and for sure there is the option of compression with the help of different methods (LZO, LZMA, gzip, ...). So far i found these 3 compression options in ...
1
vote
2answers
253 views

Debian: Create compressed Harddrive for copy

On my Debian system I have a box with certain configuration settings that I like but I've had to change them continuously. There have been times that I've gotten into a some-what irreversible ...
5
votes
1answer
267 views

What do you do to scan with 600 dpi while maintaing a small output file?

I just installed xsane which I already successfully tested with my Epson Perfection V30. When scanning with these settings the output file is remarkably large. Is there a way to decrease the size, ...
2
votes
1answer
2k views

Facility on AIX to ZIP a list of files

I'm working with an external company who is using AIX (version unknown) as their platform. They are required to FTP me a ZIP file containing multiple files. Does the UNIX utility zip exist on a ...
2
votes
1answer
4k views

Error with a .gz file decompression in Mint, but works perfectly in Windows, so the file is not corrupt

I've downloaded some .csv files from the OECD Stats website, since I need them to plot some graphs with gnuplot. When I open them with File Roller 3.4.1 (the default program to handle archive files), ...
1
vote
2answers
594 views

File compression - how to implement in Linux

I would like to be able to compress certain files (that I need to keep, but use rarely) on disk. I noticed that chattr +c flags a file for compression, but it doesn't seem to actually compress files. ...
5
votes
2answers
15k views

Having trouble uncompressing a few files [duplicate]

So I have to uncompress 4 different files. When I do file file1 file file2 file file3 file file4 for example, different messages are displayed. For example one starts like "gzip compressed data, ...
2
votes
1answer
799 views

Syslog TLS Compression and Message Buffering

Where I work, we have a site-to-site VPN tunnel set up between our main data center and a third party data center that does some Oracle PaaS for us. Since they charge per-VM, we're monitoring the ...
1
vote
1answer
1k views

How to compress wmv files on the linux console

I have some badly made WMV-files on my server that are huge (some GB) with just some picture slide-shows in it. Is it possible to compress them on the console there on the debian server so I can ...
1
vote
3answers
2k views

gzip, bzip2 and zip: very low compression ratio

I need to transfer (via ftp) some movie files (.MPG) on to remote machine. I thought to 1st compress it and then send. But all the compression utilities (gzip, bzip2 and zip) are having very less ...
8
votes
3answers
15k 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 ...
2
votes
3answers
942 views

zcat a file line by line? [closed]

I have written a C++ application that reads files line by line. It reads one line, does processing, then reads the next line. I would like to add support for gzipped files, and am looking to an ...
7
votes
5answers
22k 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/ ...
3
votes
1answer
6k 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 ...
23
votes
5answers
29k 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 ...
1
vote
0answers
112 views

problem with /compress

I have script that was provided with some SW. The script output is something like that (in debug mode). + changeDirectory + '[' -d /cdr/work/proc_raw/proc ']' + cd /cdr/work/proc_raw/proc + echo ...
-2
votes
1answer
158 views

file type determine [closed]

As part of the product, there were several scripts which was provided. In one of the scripts, I've found the following line which seems not to work properly find . -name *.old -type f -mtime +7 | ...
12
votes
3answers
2k 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 ...
3
votes
1answer
2k views

Difference between --xz and --lzma in GNU tar?

As far as I can tell, XZ is a container that uses the LZMA2 algorithm (i.e. extended LZMA); but e.g. $ xz foo/ complains about foo/ being a directory. So presumably the correct way to preserve ...
3
votes
8answers
4k 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
1answer
817 views

Will using a compressed filesystem over an encrypted volume improve performance?

Encryption/decryption is often the main bottleneck when accessing an encrypted volume. Would using a filesystem with a fast transparent compression (such as BTRFS + LZO) help? The idea is that there ...
0
votes
2answers
264 views

Can tar archiver zerofill a file?

I have received a tar archive from a co-worker and after decompresing I found that some text files are corrupted. More precisely they are filled with zeros. They have correct size but all bytes are ...
5
votes
3answers
12k views

Determine whether a particular file is compressed

How to know in Linux whether a particular file is compressed or not using a command?
3
votes
1answer
3k 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', ...
1
vote
2answers
1k views

Can I compress a compressed file more?

I have access to a server via SSH, I download files from it over SFTP or HTTP. I want to pull down a 4.4GB .mkv file but I have limited bandwidth. I have used zip, gzip and p7zip, but the file is ...
8
votes
1answer
5k 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 ...
3
votes
3answers
844 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 ...
1
vote
1answer
5k views

Uncompress txt.gz files [closed]

Trying to uncompress txt.gz files on Linux. gzip, gunzip, unzip are not recognizing the file format. The archive is guaranteed to be not corrupted.
1
vote
0answers
48 views

Is it possible to get specific information about how a file is compressed?

File compression works on the basic idea of assigning commonly recurring chains of strings to a common index of a table where the full string is stored. For example: Input file: foo bar bash baz foo ...
0
votes
0answers
29 views

How to decompress content of various archive types with one command [duplicate]

Possible Duplicate: Is there any program to provide a consistent interface across multiple archive types? I have to handle files that come as uncompressed text files or in various archive ...
2
votes
1answer
84 views

Changing compression in memory

I have some large files that I need to change the compression type of for input to a program--I need to unrar them and then gzip (or bzip2) them. However, they're highly compressed files and I don't ...
-1
votes
2answers
201 views

How to compress with bzip2 and gzip using xar?

In the "Why Xar" page of the Xar Google Code page it says: Additionally, this means xar can use different compression methods for each file in the archive. For instance, it might not be a good ...
2
votes
1answer
309 views

Backing Up to a Compressed Archive on Linux

How would you go about backing up just some files and subdirectories of a given directory to a compressed archive so that the tree structure could then easily be recreated from that archive. ...
8
votes
2answers
8k 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.
4
votes
1answer
4k 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 ...
32
votes
5answers
35k 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" ...
5
votes
2answers
724 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 ...
9
votes
4answers
22k 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 ...
2
votes
1answer
2k views

unrar part of a multipart rar file

Suppose you have a multipart rar file, say file.part1.rar, file.part2.rar, file.part3.rar. I know that I can extract only the first parts using for example unrar e -kb file.part1.rar However ...
40
votes
5answers
33k 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 ...
63
votes
7answers
45k 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. ...
42
votes
1answer
76k 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 ...
10
votes
2answers
10k 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?
28
votes
2answers
29k 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 ...
4
votes
2answers
1k 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 ...
7
votes
3answers
3k 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
1answer
1k 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 ...
3
votes
1answer
509 views

Is there an in-memory compressed swap facility (like Compcache) for FreeBSD?

Is there anything like CompCache for FreeBSD?
1
vote
1answer
4k views

Updating tar.gz daily only with changed files [duplicate]

Possible Duplicate: Add/update a file to an existing tar.gz archive? I have some game files I wish to update daily and they create a tar.gz of the folder, but instead of making a full ...
1
vote
1answer
97 views

Can someone explain what hunzip is for?

I understand what hunspell is for, but I was browsing the source code and the man, and I'm not sure: Does hunzip compress text files or just dictionaries ?