So today, I am trying to compress multiple folders, of old photos which I want to backup.
I've found this article, that says method PPMd, and compression level Ultra, are far better for image compression.
The command I'm executing is:
7z a ./output.7z /path/to/dir1/ /path/to/dir2/ -m=PPMd -mx=9
And the output has an error
7-Zip  16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21 p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,4 CPUs Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz (306D4),ASM,AES-NI) Scanning the drive: 2 folders, 318 files, 1421027053 bytes (1356 MiB) Creating archive: ./output.7z Items to compress: 320 System ERROR: E_INVALIDARG
The thing I don't understand is, since the man page, has the
-m | METHOD parameter, and the
-mx | Compression Level parameter, it stills throws an error.
Any help is greatly appreciated. Thank you, Damian G.
* Note: My OS is Ubuntu 19.04 x86_64*
* Bash Version is 5.0.3(1)-release *