I have a rather large directory, and I like to search the files for occurrence of specific strings. I have a list of about 30 strings, and my directory is 1.3G. I tried adding all the strings to a file called stringsThen I used grep -r -f strings . > grepresultsBut it takes a loooooong time. And I would not complain except I took a peek into the grepresults file, and the content does not seem to match any of my strings. I am doing something wrong. What should I do to see the result of my command immediately, and verify that it is what I want. Then I have no issue letting it run. Please let me know, and I'll post a sample of what it sends currently. I issued grep -rFf foo -o and seems to get a whole bunch of irrelevant content. I do not know how to use stdout. Could you provide more detailed instructions please? 
How to check for specific strings in files of a large directory
ubuntu;grep
(Extracted answer from edit)I got the result of the search by letting it run overnight. The command I used was:@ubuntu:~/WORKING_DIRECTORY/LC_ALL=C fgrep -rFf bar > ~/myfileMoving the results file, called myfile in the above command, definitely helped.I also sorted the strings in the file. It was originally called strings, and I learned from one of the comments in this thread to change it to another name. So in the above command it is called bar. Using LC_ALL=C and fgrep instead of grep helped immensely. All the suggestions contributed to the answer.