Prueba de Linux si la cadena existe en el archivo
if grep -Fxq "string" file.txt; then
echo "Match"
else
echo "No match"
fi
bougui
if grep -Fxq "string" file.txt; then
echo "Match"
else
echo "No match"
fiJust use grep with flags 'F' (fixed string), 'x' (exact match) and 'q'
(quiet output) in order to check if a word string is in a file
if ! grep -Fxq "string" file.txt; then #do some code...#; fi