Print all lines containing the keyword test:
grep test file.txt
Create a file that has all the keywords, one per line and run:
grep -f keywords.txt file.txt
Process a file line by line, exit if the line is found:
while read line; do echo $line | grep test && break; done < file.txt
while read line; do let c++; echo $line | grep test >/dev/null; if [[ $? == 0 ]] ; then echo Match for line $c : $line; else echo No match for line $c; fi done < file.txt