Keep lines containing a word or phrase that you specify, or keep the lines that don’t have that word or phrase (click “Show Example”).
You can also ignore case, match only whole words, and sort results. Paste lines, select options, and press Submit. Results appear at the bottom of the page.
Starting with this list:
cat
dog
mat
a big chubby hog
If you keep lines with “at” in them, you will be left with
cat
mat
If you remove lines with “at” in them, you will be left with
dog
a big chubby hog
“Therefore encourage one another and build each other up, just as in fact you are doing.”
– 1 Thessalonians 5:11