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Questions tagged [compression]

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

Questions related to technology which shrinks (compresses) and restores (decompresses) data using a mathematical algorithm.

419 questions
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How does the ent program calculate "optimum compression"?

The ent program can be run on a file to give output such as the following: Entropy = 4.731183 bits per byte. Optimum compression would reduce the size of this 15731 byte file by 40 percent. Chi square distribution for 15731 samples is 235086.62,…
jl6
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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 program capable of taking an advantage from the fact,…
maaartinus
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Is there a compression method that supports solid compression and also adding data to the compressed file?

I have a large compressed .tar.xz file containing log files. The compression ratio is very good - but it takes a long time to compress, and if I want to add additional log files to it, I have to extract it, add the new file, and recompress it -…
jl6
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Time-adaptive compression tool

I'm asking about a scenario of copying a big file to a remote server. A simplest case is: tar c myfile | ssh myserver tar x If network connectivity is fast then all is fine. On a slower network I do tar c myfile | bzip2 -1 | ssh myserver tar xj --…
bohdan_trotsenko
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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 system) and then mounting it with the -o loop option.…
Doc
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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 using the compress command in UNIX, but it is not…
PriB
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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 always 4.4GBs after the compression process. After…
Baldrick
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How to compress .cbr and .cbz files very tightly?

I am wondering how to compress .cbr and .cbz files very tightly to decrease the file size.
Anonim
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Resumable compression

I'm in the process of compressing a very large file (several TBs) with the following command, and it's been running for several days. tar -I pigz -cf /path/to/compressed.tgz /dataset/to/compress I'm slightly worried that I'll lose these days of…
bjd2385
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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 compression ratio. For…
Ravi
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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 'Changed to the directory:…
user1977050
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Are there any compression algorithms that create identical files on Linux and Mac?

This question and answer (GZip doesn't produce the same compressed result on macOS vs Linux) are pretty clearly the GZIP doesn't meet the bill. No argument there. But, I think the real question lurking behind that question is: Are there any…
Thomas Jay Rush
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Is it possible to change the zlib-flate compression level?

I use the zlib-flate compression utility. Is it possible to compress at different levels. The man page information is pretty vague. If not is there an alternative utility that allows you to compress using zlib at different levels?
0siris
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compress multiple files at once but don't put them all into one file?

I want to compress multiple files at once (one command) but I don't want to put them into same directory or same file. How'd I do it?
achhainsan
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See the file name and size within a (.Z) compressed file without uncompressing it

I have tons of .Z compressed files scattered across various directores and need to see the size of the file within it. I don't plan on uncompressing all the .Z files. Is there a way to see the content (typically 1 file) the size of? I am aware of…
Steve237
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