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I have a file with some non-printable characters that come up as ^C or ^B, I want to find and replace those characters, how do I go about doing that?

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7 Answers 7

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Removing control symbols only:

:%s/[[:cntrl:]]//g

Removing non-printable characters (note that in versions prior to ~8.1.1 this removes non-ASCII characters also):

:%s/[^[:print:]]//g

The difference between them could be seen if you have some non-printable-non-control characters, e.g. zero-width space:

enter image description here

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12 Comments

At least until vim 7.3 [:print:] only matches ASCII printable characters (edited the answer to alert readers about this fact)
@ndemou This is tricky, with the [ ] around the [:print:] the ^ should invert the match and return any non-printable. Or perhaps that was your edit?
@dragon788, yes I was aware of how it works when I wrote my comment. Try the 2nd regex on text with printable Unicode characters outside the ASCII table to understand my comment (it will remove the Unicode characters).
@ndemou Have it changed in recent versions of Vim? I don't see any difference in the behavior of these two regexs in 8.1.1. Here is the screenshot: imgur.com/a/NHS5EHr . Also, it doesn't remove non-ASCII characters, e.g. Chinese and Russian (the last part isn't something bad, just to point the difference).
@john-c-j I've just confirmed your observation. It was a bug anyway to consider printable Unicode characters as non printable. -- updated the answer (& waiting for peer review)
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51

Say you want to replace ^C with C:

:%s/CtrlVC/C/g

Where CtrlVC means type V then C while holding Ctrl pressed.

CtrlV lets you enter control characters.

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You can also use Ctrl-Q. This is useful for some users who map Ctrl-V to clipboard operations
15

Try this after saving your file in vim (assuming you are in Linux environment)

:%!tr -cd '[:print:]\n'
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@JamesAndino: :% filters all lines using the external (!) programm tr, which removes (-d) all characters that are not (-c) printable ([:print:]) or newline (\n).
This isn't Unicode friendly, as it is a POSIX character class (en.wikipedia.org/wiki/Regular_expression#Character_classes). So if you have YAML with data like 你好, tr will strip the Unicode data when using [:print:].
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None of the answers here using Vim's control characters worked for me. I had to enter a unicode range. 

:%s/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\x9F]//g

That unicode range was found on this other post: https://stackoverflow.com/a/8171868/231914

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Because TAB is considered not-printable, So these [[:cntrl:]] and [^[:print:]] match TAB (0x9, C-I)
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An option not mentioned in other answers.

Delete a specific unicode character with a long hex code, e.g. <200b>:

:%s/\%U200b//g
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This was what I was looking for! See vimdoc.sourceforge.net/htmldoc/pattern.html
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You can use:

:%s/^C//g

To get the ^C hold the control key, press V then C (Both while holding the control key) and the ^C will appear. This will find all occurrences and replace them with nothing.

To remove both ^C and ^B you can do:

:%s/^C\|^B//g
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5

You can use the CTRL-V prefix to enter them, or if they're not easily typeable, yank and insert them using CTRL-R ".

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