Use filter commands to process text
From Vim Tips Wiki
created 2002 · complexity basic · author zzapper · version 6.0
Here are some examples of filtering which show how to save output from Vim commands, or read text from a file, or send text to an external program while capturing the output from that program.
 Capturing output
Redirection can capture the output generated by Vim commands.
Redirection to clipboard register
+ (or use any other register a-z):
:redir @+ :history :g/fred/ " any other commands :redir END
The output from the commands used is now in register
+ which might pasted into a new buffer, for example by entering
:new then typing
"+p to paste.
If wanted, you can temporarily turn off Vim's paging so there will be no "More" prompts, as shown in the following example which outputs to register
A (so output is appended to register
:redir @A :set nomore :echo 'History' :history :echo 'Scripts loaded' :scriptnames :set more :redir END
Redirection to a file:
:redir > out.txt :registers " any other commands :redir END
The above writes to the new file
out.txt. The command does nothing if that file already exists. To overwrite the file if it exists, use
:redir! > out.txt. To create a new file or append to an existing file, use
:redir >> out.txt.
Store glob results in register
" Clear @a (register a) because need to use A to append. :let @a = '' " Append all lines containing 'fred' to register a. :g/fred/y A " Append to a file (must use >>). :'a,'b g/^Error/ .w >> errors.txt
The last command uses the
:.w command which writes the current line (
.) by appending it to file
 Processing input
Get output from external commands:
:r !ls " read output from running ls, after current line :0r !ls " after line 0 (before first line) :-r !ls " before current line ("-" is ".-1") :r !dir " use 'dir' on Windows
Filter current file using an external command (these examples use
sort, but Vim has a built-in :help :sort command which should be used to sort lines):
:%!sort -u " use an external program to sort all lines :'a,'b!sort -u " same, for lines from mark a to mark b inclusive
The term "filter" means to replace lines with the result from running a program. The original lines are sent as stdin to the program, and are replaced with stdout from the program. You can also filter using motion commands or visual selection:
!}sort " sort from cursor to end of paragraph 3!}sort " same, 3 paragraphs 3!!sort " sort 3 lines V " start visual selection of lines (move cursor) " select some lines !sort " sort the visually selected lines
 Simple filter example
Following is a Python program to sort the words on each line of standard input (each line is separately sorted).
# File sortwords.py from sys import stdin for line in stdin: print ' '.join(sorted(line.split()))
A file you are editing in Vim may include the following text:
this is a line with some words words on each line will be sorted fried banana and cream
Use this procedure to filter the text:
Von the first line, then
jjto select three lines.
!python sortwords.pyand press Enter.
The lines are replaced with the result from running the program:
a is line some this with words be each line on sorted will words and banana cream fried
The section about redirecting Vim commands has nothing to do at all with using filters, and neither does the stuff about :r !cmd. That plus the actual stuff about filters seems redundant with the content in Append_output_of_an_external_command. --Fritzophrenic 14:25, July 2, 2012 (UTC)