Searching multiple patterns (words) with ack?

Question

I want to search multiple patterns in a directory containing recursive directories and files.

I know command for

Answer 1

This should be enough:

ack -R 'string1|string2'

As -R is the default, you can omit it:

ack 'string1|string2'

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From man ack:

-r, -R, --recurse

Recurse into sub-directories. This is the default and just here for compatibility with grep. You can also use it for turning --no-recurse off.

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If you want to get the pattern from a file, say /path/to/patterns.file, you can use:

ack "$(cat /path/to/patterns.file)"

or equivallently:

ack "$(< /path/to/patterns.file)"

I cannot find an exact equivalent to grep -f.