created 2002 · complexity basic · author tarjei · version 5.7
The ex command
g is very useful for acting on lines that match a pattern. You can use it with the
d command, to delete all lines that contain a particular pattern, or all lines that do not contain a pattern.
For example, to delete all lines containing "profile" (the first command is optional; it shows the lines that the second command will delete):
More complex patterns can be used, such as deleting all lines that are empty or that contain only whitespace:
To delete all lines that do not contain a pattern, use
g!, like this command to delete all lines that are not comment lines in a Vim script:
g! is equivalent to
v, so you could also do the above with:
The next example shows use of
\| ("or") to delete all lines except those that contain "
error" or "
warn" or "
fail" (:help pattern):
Can we remove all even numbered lines in a file using this feature. can we do some kind of math in the pattern. (ex: \=line(".") % 2)
Not really, but you can do that in two steps:
:g/.*/if line('.')%2|call setline(line('.'), '===delete===')|endif :g/^==delete==$/d
If you simply put delete inside the if statement all the lines will be deleted. In this way you can delete lines from several different ranges:
:let range = range(10,15)+range(20,25)+range(30,35) :g/.*/if index(range, line('.')) != -1|call setline(line('.'), '===delete===')|endif :g/^===delete===$/d
But I think the faster way to do that is to use :[range]d several times. Another solution is to use exe to build a pattern:
exe "g/".join(map(filter(range(line("$")), 'v:val%2'), '"\\%".v:val."l"'), '\|')."/d"