Oracle equivalent to Sybase's xp_cmdshell?

Hello, all!

I'm eager to learn if Oracle has an equivalent to Sybase's xp_cmdshell
extended stored procedure.  The xp_cmdshell function essentially shells out
to the OS and executes the provided string.  One of the nice features of
xp_cmdshell is that it will return the output as rows of text and can thus
be handled as a result set you can cursor through.

I'm having a tough time figuring out how to execute an OS command from
Oracle, in general.  Would DBMS_PIPE be something that can be leveraged?  Is
there something like xp_cmdshell?

Thanks for your help!  :-)