I want to know more information about a process running on my Unix/Linux system (memory

used, options, arguments, parameters passed on the command line, etc)

A command such as this will provide a great deal of information about a process:

ps -eo user,group,pid,ppid,rss,vsz,comm,args | grep <process name>

For exmple, if you only want the total size of the p_sftpsock process, the following command will give you this information:

ps -eo vsz,fname | grep p_sftp