grep -f when the pattern file also has some empty lines

Question

Is there any option of the grep command to suppress the effect of empty lines in the pattern file? I would prefer this option than always checking and filtering the nascent pattern file.

Here is an example (in pattern_file , there is an empty line):

$ cat pattern_file  
APPLE  

PEAR  
$ cat file  
Nothing  
fruit  
$ grep -f pattern_file file  
Nothing  
fruit

Answer 1

要忽略病毒码文件中的空行：

grep -f <(grep . pattern_file) file

Answer 2

grep -v '^$'

This actually grabs all the lines except for newlines. You can pipe the result to your grep like this: grep -v '^$'| otherGrep grep -v '^$'| otherGrep

Answer 3

About -f option:

A null pattern can be specified by an empty line in pattern_file .

So, it is a feature, and you should delete empty lines , eg with sed :

sed '/^$/d' | grep -f ...