how do i search for a file in ubuntu code example

Example 1: ubuntu search file in specific folder

// Using backslash and asterisk (\*) at the end will search for all files that start with your search term (in this case "readme"). So you would also be able to find "readme2" etc. 
find . -name readme\*

Example 2: how to search in directory files in ubuntu

# this will search all subdirectories for your text (no case sensitivity)
# it also prints the line number of the text in file
grep -inR "your text" .