The ps command can group processes based on the real and effective usernames or IDs specified. The ps command filters the output by checking whether each entry belongs to a specific effective user or a real user from the list of arguments.

• Specify an effective user's list with -u EUSER1, EUSER2, and so on
• Specify a real user's list with -U RUSER1, RUSER2, and so on

Here's an example of this:

    # display user and percent cpu usage for processes with real user
    # and effective user of root
    $ ps -u root -U root -o user,pcpu

The -o may be used with -e as -eo but when filters are applied, -e should not be used. It overrides the filter options.