Add Rename Current File to vim til.

vim/rename-current-file.md

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+# Rename Current File
+
+Vim doesn't come with an easy way to rename the existing, current file. The
+closest you will get with a one-off command is `:saveas {new file name}`
+which renames the current buffer, but also leaves you with your old file.
+
+Another approach that you can take is to chain two commands together. You
+can start be *deleting* the current file (don't worry, you've still got the
+file contents in your buffer) and then *saving* the buffer with the new
+name. Like so:
+
+```
+:call delete(expand('%')) | saveas new-file-name.txt
+```
+
+While this seems to do the job well enough, your mileage may vary.
+Consider using a more robust plugin, such as
+[rename.vim](https://github.com/danro/rename.vim/blob/master/plugin/rename.vim).