Removing Blank Lines

Here's a handy one-liner to remove blank lines from a file.

:g/^$/d

Breaking this down. The "g" will execute a command on lines that match a regular expression. The regular expression matches blank lines, and the command is "d" (delete).

Reverse Lines in a File

You can quickly reverse all lines in a file using the following ex command.

:g/^/m0

This is particularly useful for files that are in chronological order such as logs or email mbox files. Thanks to Skyler for submitting the tip.

Remove Empty Lines

Here's a quick sub to remove all the empty lines in a file. I use this to cleanup after macros that leave a bunch of blanks.

:%s/^\n//