Sometimes on linux/unix computers, you will want to do a search for any files containing a particular string within it. This can be particularly useful when searching for specific things for a CI/CD pipeline.

On linux or mac, if we want to search a set of files for a specific string in a terminal, we use the grep.

Find all files which contain a particular string on Linux or Mac

Return the filename only

The below will find any file that contains the term 'html' in the '/views' directory. It will return only the file names.

grep -rl ./views -e 'html' 

Return the text itself

Again, this will find any file containing the string 'html' in the '/views' directory. It will return the line which has that text in it.

grep -r ./views -e 'html' 

How to use grep on Linux/Mac

You can string other options together, to get different results. When we say -r, for example, we mean 'recursive' - i.e. it will search through every folder. When we write -rl, this means essentially -r -l, which means search recursively, and return only the file name.

Below is a list of all grep options or switches, which you can add to your query to get the results you need:

1. -r - search recursively.
2. -l - return only the file name.
3. -i - ignore the case.
4. -w - search only for words, i.e. not text within words. For example, if we search for 'html', then somehtmltext would not match.
5. -n - returns the line number, but doesn't work with -l.
6. -s - suppress any error messages.
7. -h - output the line itself, without the line number or file.
8. -v - invert the search, i.e. searching for html with -v will return everything without html.
9. -f - used to indicate a file you want to use which contains a regular expression.
10. -x - match only if the whole lines only. This will only return for a search of html if that exists on its own line separately.