You could always install
ksh on Linux. Which flavour are you going to?
That will get you close, but often
ksh is a link to
bash which then emulates the
ksh functionality closes but not exactly. I'm an AIX person more than anything else, but
generally scripts should be transferable. Testing is definitely required though. As for
csh, try to re-write it and get rid. There are many arguments to get rid of
csh, including
Csh Programming Considered Harmful
Compiled code, on the other hand, will need to be either compiled again if it is your own, or the correct version from your supplier needs to be installed for your particular flavour of the OS.
As a general assistant, you also have
Rosetta Stone for Unix to help with all the "It's the same, but different!" issues. Sadly there is no
mksysb by default, but there are commercial and free options, depending on your needs.
I hope that this helps,
Robin