I have read that the ps command can take flags in two format:The Unix format in which you should precede the flagswith a dash.The BSD format in which you should not precede the flags with adash.Now does the same flags can be used with both formats, for example do the following commands mean the same things:ps -xps xOr does the Unix format has its own set of flags, while the BSD format has an entirely different set of flags?
Confused about the meaning of Unix vs. BSD flags format for the ps command
linux;ps
The manpage answers your question:Options of different types may be freely mixed, but conflicts can appear. There are some synonymous options, which are functionally identical, due to the many standards and ps implementations that this ps is compatible with.Note that ps -aux is distinct from ps aux. The POSIX and UNIX standards require that ps -aux print all processes owned by a user named x, as well as printing all processes that would be selected by the -a option. If the user named x does not exist, this ps may interpret the command as ps aux instead and print a warning. This behavior is intended to aid in transitioning old scripts and habits. It is fragile, subject to change, and thus should not be relied upon. The flags are different, but can be combined. Typically youd pick one though, e.g. either ps aux or ps -ef to see details of all processes, not a mixture.The only x flag is the BSD one, so ps x and ps -x produce the same result; but that doesnt work for flags defined in both variants.