Versions 1.20.* and 1.21.1 do not implement the xz compressor correctly. Whenever used, it merely displays the usage (-h) but does nothing. My desktop allows me to type 'xz file' and get a file.xz
Yes, it's true. We don't have XZ *compressor*, only decompressor. Help says exactly this - that option -d is mandatory: BusyBox v1.21.1 (2013-12-16 01:47:36 CET) multi-call binary. Usage: xz -d [-cf] [FILE]... Decompress FILE (or stdin) -d Decompress -c Write to stdout -f Force See? it is not "[-d]", it is "-d". Config help says the same: CONFIG_XZ: Enable this option if you want commands like "xz -d" to work. IOW: you'll get xz applet, but it will always require -d option.