Edit a file and:
- explicitly set RCS keywords to be expanded (k)
- have the executable bit set (x)
- always be writeable on the client (w)
or if it's already being edited:
p4 reopen -t text+kxw
See also
p4 help filetypes
+w always writable on client
+x exec bit set on client
+k $Keyword$ expansion of Id, Header, Author, Date, DateTime, Change, File, Revision
+ko $Keyword$ expansion of Id, Header only
+l exclusive open: disallow multiple opens
[full article]