grep, awk, sed family tool
Grep
Global Regular Expression Pattern
With grep you can do simple text-based or regular expression search on the file you passed or can be also piped.
You can only provide in one pattern, you can provide in multiple pattern to search for by using the pipe symbol, but any parameter after the pattern are treated as filenames
Use the -E flag to use the extended regular expression notation, i.e. you don't have to escape the following character to get their special meaning, ?, +, {}, and | in the regular expression.
Usages
grep <insert word to search> filename |
This will perform a search on the entire file to find where the word occurs |
grep -i <word> filename |
Perform a case-insensitive search on the entire file |
grep -R <word> . |
Perform a search on all of the file in the current directory as well as the sub-directories |
grep -c <word> filename |
Count the number of matches |
grep -A -B -C <word> filename |
Use -A, -B, and -C to get context surrounding the matched text, after, before, and both before and after respectively |