Is there a htop-on-linux like alternative for top / Activity Monitor on OS X?

Solution 1:

You can install htop on Mac through brew with the following command:

brew install htop-osx

Don' t forget to grant root privileges after the installation.

Solution 2:

Sending of signals and filtering by user is available out of the box. From man top

   INTERACTION
          When top is run in interactive (non-logging) mode, it is possible to control the output of top, as well as  in-
          teractively  send  signals to processes.  The interactive command syntax is terse.  Each command is one charac-
          ter, followed by 0 to 2 arguments.

   S<signal><pid>
          Send <sig> to <pid>.  <sig> can be specified either as a number or as a name (for example, HUP).   The  default
          signal  starts  out as TERM.  Each time a signal is successfully sent, the default signal is updated to be that
          signal.  <pid> is a process id.

   U<user>
          Only display processes owned by <user>.  Either the username or uid number can be specified.   To  display  all
          processes, press enter without entering a username or uid number.

If you want to extend top yourself, the source code is available on http://opensource.apple.com.

Solution 3:

You can use process explorer for OS X - http://newosxbook.com/ has that as a free download. It's modeled after Linux top, and is much more powerful than Apple's own.