Condición esperada: Grep
if [ "$(cat textfile.txt | grep 'search string')" = "" ]; then; echo "some string"; fi;
DreamCoder
if [ "$(cat textfile.txt | grep 'search string')" = "" ]; then; echo "some string"; fi;if [ "$(cat textfile.txt | grep 'search string')" == "" ] ; then
echo "It's not there!"
fi