I'm currently engaged in moving a bunch of things from VM/CMS to Linux.
Most of it is written in Rexx with a lot of Pipelines. The Rexx part
has proved to be pretty easy -- ooRexx is mostly compatible and mostly
an improvement. The Pipeline part is a lot tougher. I sure wish CMS
Pipelines could be ported to Linux (and Mac OS X, for that matter;
ooRexx works there as well). I miss Xedit, but THE is almost as good
and works pretty well with ooRexx. THE lacks update support, which
would be a big help, but I'm sure that would be a complicated thing to
implement. Actually, a CMS shell that ran under Linux would be pretty
neat. There is always a Linux replacement for a VM/CMS feature, but
often it isn't nearly as nice. A lot of times rethinking something from
the CMS way to the Linux way helps, but sometimes not. Some things are
actually easier with Linux. I wish IBM had done some things differently
10 years ago.