Or ps, with its BSD and SysV variants. On Linux, the most widely used version of ps uses BSD semantics when using options without a dash, and SysV semantics fo

Or ps, with its BSD and SysV variants. On Linux, the most widely used version of ps uses BSD semantics when using options without a dash, and SysV semantics for dashed options. Thus, both BSD “ps aux” and SysV “ps -fel” work.