In GPT/BIOS, GRUB2 "installs" on BIOS boot partition "core.img" consiting of "diskboot.img", lzma decompressor (lzma_decompress.img) and core.img (IIUC). I assumed that skipping 512 B of diskboot.img, then skipping lzma decompressor (2880 B on SLES), I would get compressed "real" core.img (ending where '00 00' follows). But how to decompress this part? Or, do I do anything wrong? BTW, I can't decompress even /boot/grub2/i386-pc/core.img (on SLES too) while skipping same parts... The goal is to see real "core.img" data to detect a modification...

Until now, I used to backup my data using tar with one of the LZMA compression options (--lzma, --xz or --lzip) I recently noticed that 7-Zip has been ported to Linux in 2021 (https://www.xda-developers.com/7-zip-linux-official-release/) . I'm not talking about the older P7Zip (https://p7zip.sourceforge.net/) , that doesn't seem to be maintained anymore, but about the official 7-Zip. So, I tested it, and was very surprised to discover that it's A LOT faster than all the others Linux LZMA implementations, for the same compression ratio. Below my tests (Debian 11). Please not that I emptied the RAM cache between every test (sync && echo 3 > /proc/sys/vm/drop_caches) I am working on a 163M folder, containing several type of files, PDF, text, open office, and so on...

$ du -hs TEST/
163M	TEST/

With 7-Zip it's compressed into a 127M file in 15 seconds :

$ time tar c -hp TEST/ | 7zz a -si test.tar.7z
real    0m14,565s
(...)

$ ll test.tar.7z
(...) 127M (...) test.tar.7z

Whereas with all the other implementations of LZMA, it takes almost 5 times longer (around 1'13"), for the same archive size !

$ time tar -chp --lzma -f test.tar.lzma TEST/
real    1m13,159s

$ time tar -chp --xz -f test.tar.xz TEST/
real    1m12,889s

$ time tar -chp --lzip -f test.tar.lz TEST/
real    1m12,525s

$ ll test.tar.{7z,lz*,xz}
(...) 127M (...) test.tar.7z
(...) 127M (...) test.tar.lz
(...) 127M (...) test.tar.lzma
(...) 127M (...) test.tar.xz

Just to be sure there's nothing wrong with tar, I did the same tests but piped tar's output to lzma|xz|lzip, instead of using the --lzma, --xz and --lzip switches. Same results. So, basically, 7-Zip's Linux version makes all other LZMA implementations look rather bleak. I think 7-Zip doesn't support Linux owners and permissions, but that's irrelevant when compressing a .tar file. So, does anybody know why 7-Zip's Linux version is so much faster than other LZMA implementations ? ```

The following script

mkdir test && cd test
mkdir files
touch files/{1,2,3}
tar --create --file "test.lzma" files/{1,2,3} --auto-compress
mkdir extracted_files
tar --extract --file "test.lzma" --directory extracted_files --auto-compress

produces the following error: > tar: This does not look like a tar archive but actually tar+compress and uncompress+untar do happen (files are in place). Why is this happening? Is it some kind of bug in tar? On my system:

xz --version
 xz (XZ Utils) 5.2.7
 liblzma 5.2.7
tar --version
 tar (GNU tar) 1.34
file test/test.lzma
 test/test.lzma: LZMA compressed data, streamed
ls test/extracted_files/
 files

You can also reproduce it in https://replit.com/languages/bash (with xz (XZ Utils) 5.2.2 and tar (GNU tar) 1.34). But not in https://www.onlinegdb.com/online_bash_shell (with xz (XZ Utils) 5.2.4 and tar (GNU tar) 1.30).

help with the firmware file of the radio. I unpack the file with the 7zip program, with the same program I can not return the file back to its original state with the same file size. https://cloud.mail.ru/public/u68D/xpEJ56GWH

I installed recoll on my Kubuntu 20.04. Now it says that external apps and commands are missing that are required for the indexing are missing, specifically: djvutxt (image/vnd.djvu) python3:pylzma (application/x-7z-compressed) but I have no idea how to install them. No such packages are shown in muon (my package manager GUI). How can I install them?

I did compress a directory to .tar.xz archive format with this command: tar --create --verbose --file myArchive.tar.xz /path/to/my/dir then,I tried to check health of created archive with following command: tar --compare --file myArchive.tar.xz /path/to/my/dir and I got this error lines : tar: /path/to/my/dir: Not found in archive tar: Exiting with failure status due to previous error I retried it but got same resault.what is the problem and how can I solve it?

I wanted to compress a directory whit size of about 25 GB to .tar.xz format using following command: tar --xz --create --verbose --file myArchive.tar.xz /patch/to/my/dir but got these error lines: xz: (stdout): Write error: file too large tar: myArchive.tar.xz: wrote only 2048 of 10240 bytes tar: Child returned status 1 tar: Error is not recoverable: exiting now I tried it for .tar.gz format too and got approximately same error lines. I am using Fedora 32 and the destination file system is W95 FAT32(LBA). The file stopped writing at about 4.3 GB. What's strange is that my disk has more than 500GB free space. What is the problem and how can I fix it?

I wanted to compress a directory into .tar.xz format and verify it after writing so I wrote a command like this: tar --xz --create --verbose --verify --file myArchive.tar.xz /patch/to/my/dir but it did not create archive and I got this two error lines: tar: Cannot verify compressed archives try 'tar --help' or 'tar --usage' for more information. I tried tar.gz format instead of tar.xz but got exactly same resault, what is the problem and how can I solve it?

I have an lzma compressed file that I've extracted from a firmware image (via binwalk) that is X bytes uncompressed and Y bytes compressed. When I try to compress the extracted file again - without any modification and using the same compression ratio - on my machine (Ubuntu 18.04), I end up with a compressed image that is Z bytes instead of Y bytes. My guess is that is has to do with the version of lzma that I'm using vs the version that was originally used - is that correct? And if so, is there a way to tell which version of lzma was used originally? Also, the compressed file extracted from binwalk has the .7z extension, but running file orig_compressed.7z says that it's an lzma file. I'm not sure if that's making a difference. Edit: the firmware uses the MIPS architecture - I've tried using qemu-system-mipsel to run the MIPS lzma and I still got a compressed file that was a different size than what I'm expecting it to be.

I've tried several invocations of the OEM tar to create LZMA-compressed tarballs. More specifically, I tried: tar -c -f --lzma Windows\ 7.vmwarevm.tar.lzma Windows\ 7.vmwarevm My efforts created an archive with filename --lzma, and tar complained of Windows 7.vmwarevm.tar.lzma: Cannot stat: No such file or directory, probably for the same reason: --lzma was taken as the filename of the archive to be created, and consequently the actual intended archive name was taken to be the first in a list of arguments to include in the archive. I thought after some searching that MacOS had not included it in the provided options, and built GNU tar from scratch, storing it under another name in /usr/local/bin. However, my efforts to use the above invocation with the renamed and newly built tar had the same effect: I was building an archive in --lzma. My computer has a seemingly working /usr/local/bin/lzma. What invocation(s) should I use, perhaps piping tar to lzma and perhaps in a script to do the work of "tar czf foo.tgz foo", but uses lzma instead of gzip for compression?

I have a 44GB 7z compressed file that I compressed with lzma2 and it took around 11 hours (original file is a text file of 285GB). 7z a -t7z Files.7z -m0=lzma2 -mx=9 -aoa So, what I want is to do is to split the file without re-compressing it, to be able to upload/download over simultaneous connections How would I split and join such a file without going through the 7z recompress process again?

Similar to for GZIP archives I need a way to get the trailing data of an LZMA archives.