How to grep with a list of words

Question

I have a file A with 100 words in it separated by new lines. I would like to search file B to see if ANY of the words in file A occur in it.

I tried the following but does not work to me:

grep -F A B

score 137 · Accepted Answer · edited Aug 23 '14 at 08:00

137

You need to use the option -f:

$ grep -f A B

The option -F does a fixed string search where as -f is for specifying a file of patterns. You may want both if the file only contains fixed strings and not regexps.

$ grep -Ff A B

You may also want the -w option for matching whole words only:

$ grep -wFf A B

Read man grep for a description of all the possible arguments and what they do.

edited Aug 23 '14 at 08:00

legends2k

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answered Jul 25 '13 at 16:12

Chris Seymour

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Is -F just an optimization if you don't want to use regexps? – Simd Jul 25 '13 at 18:34
What about finding all occurrences of words in file A in a *directory tree B*, listing only the filenames of all matches in B? – zealoushacker Sep 24 '14 at 05:00
@zealoushacker -H to also print the filename. – Brandon Langley Feb 12 '22 at 02:12

score 3 · Answer 2 · edited Aug 21 '23 at 16:13

3

To find a very long list of words in big files, it can be more efficient to use egrep:

# remove the last \n of A
$ tr '\n' '|' < A > A_regex
$ egrep -f A_regex B

edited Aug 21 '23 at 16:13

Benjamin Loison

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answered Dec 16 '14 at 15:22

Alcolo47

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How to grep with a list of words

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