usage:     psg [-v] [-ps-options] ['expression'] [pattern]
   or:     psg [-v] [+fields] ['expression'] [pattern]
   or:     psg '/path/to/ps ps-options' ['expression'] [pattern]
   or:     psgt pattern
options:   -v           verbose mode
	   -ps-options  any legal ps options combination
	   +fields	add user format fields (see man ps)
arguments: pattern is a Perl regular expression (or just a substring)
           expression is a ps field element comparison. Possible operators are:
                =         : equal
                <>        : not equal
                <         : numeric less
                >         : numeric greater
                <=        : numeric less equal
                >=        : numeric greater equal
                $<        : string less
                $>        : string greater
                $<=       : string less equal
                $>=       : string greater equal
                =/.../    : pattern matching
                <>/.../   : inverse pattern matching
                $VAR      : environment variable VAR
                FIELD:    : no comparison, but sort for FIELD
                tree:PID  : no comparison, but show process tree for PID
                tree:USER : no comparison, but show process tree for USER
	   (logical operators && || () are allowed, too)
examples:  psg login
           psg 'USER=framstag'
           psg 'USER=/frams/' sh
	   psg 'COMMAND<>/-/'
	   psg 'PID<200 && USER<>root'
	   psg 'CPU:'
	   psg 'TREE:framstag'
	   psg '/usr/ucb/ps -lww' sendmail
           psg +state perl
           psgt inetd