You need to search for the string “Tecmint” in all the “.txt” files in the current directory. How will you do it?

above command won't tell which file(s)  has the word Techmint, i think more appropriate is to use grep  -n Techmint  *.txt

grep -i "Tecmint" *

This will show the files if it is contained any of the file

$ grep -i "Techmint" *.txt, would to that for both the cases, with content and files. 

$ grep -l Techmint *.txt , would list the files containing the string. 

grep Tecmint *.txt