How to grep the result of a grep?

Question

I need to grep some files to see which ones contain a certain word:

grep -l word *

Next I need to grep that list of files to see which ones contain a different word. The easy way would probably be to write a script but I don't know quite how to work it.

Answer 1

Assuming none of the file names contain whitespace, single quote, double quote or backslash characters (or start with - with GNU grep), you can do:

grep -l word * | xargs grep word2

Xargs will run the second grep over each file from the first grep.

With GNU grep/xargs or compatible, you can make it more reliable with:

grep -lZ word ./* | xargs -r0 grep word2

Using -Z makes grep print the file names NUL-delimited so it can be used with xargs -0. The -r option to xargs avoids the second grep being run if the first grep doesn't find anything.

Answer 2

grep -l word1 $(grep -l word2 *)

or maybe for one of the two words on the same line:

grep -w 'word1\|word2' *

see here

Answer 3

If you need to find files containing a word and then filter out those files containing another word, you could use a sequence of commands like this:

grep word * | awk -F ':' '{print $1}'|uniq | xargs grep word2

• grep word * - will show all files containing "word", the filename will be first in the list.
• awk -F ':' '{print $1}' - will print only the filename of your results
• uniq - will make sure that you do not print the filename more than once.
• xargs grep word2 - will again search in the list of files you got.