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 
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3 Answers
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.
3 Comments
Simd
Is -F just an optimization if you don't want to use regexps?
zealoushacker
What about finding all occurrences of words in file A in a directory tree B, listing only the filenames of all matches in B?
Brandon Langley
@zealoushacker -H to also print the filename.
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 
Comments
Use extended regular expression, invoke grep the -E ( or --extended-regexp) option:
grep -E 'pattern1|pattern2' file...