Grep

grep -rnw '/path/to/somewhere/' -e 'pattern'

• -r recursive
• -n line number
• -w match the whole word.
• -l list the file name
• -e what follows is the PATTERN to search for.
• -A <number> print the matching line, then this many lines afterwards.

References

Find all files containing a specific text (string) on Linux - Stack Overflow