Clean up a lot how the ssh search is generated and maintained.

ssh/prologue

@@ -3,10 +3,7 @@
 #
 # That config uses Canonicalization to emulate what your local resolver
 # does in these circumstances.
-Match exec 'rm -f ~/ssh/search | false'
-
-Match exec 'grep "^search" /etc/resolv.conf ' exec 'grep search /etc/resolv.conf | awk \'{print "Host *\n\tCanonicalDomains "$2"\n\tCanonicalizeHostname yes\n# v""im:ft=sshconfig"}\' > ~/.ssh/search'
-
+Match exec "~/cshenv/ssh/gen-search.sh"
     Include ~/.ssh/search
 
 # vim: ft=sshconfig