grep
Case-insensitive grep a file for a word/term
grep -i "some term" somefile.txt
Grep if there are binary matches found
cat somefile.txt | grep -i match --text
Match whole words in a file
grep -w 'hi' somebigfile.txt
Search for word in file but still display rest of the file and only highlight matches
grep -i "REMOVE\|" log
Source: Twitter