Using vi how to obtain a number of time a word or pattern occur in the file

How do calculate the number from inside开发者_运维技巧 the vim?

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For counting the number of times some pattern occurs, use:

:%s/pattern//gn

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The following will work with unmodifiable files, and the result can be kept and used elsewhere in our scripts.

:let g:n = 0
:g/pattern/let g:n += 1
:echo g:n