grep
looks like regular expression matches in text, and is a very versatile tool.
Here is the GNU grep manual.
Here are some handy invocations:
adb devices | grep device$
grep -RF feedback
grep -RF --include '*.md' --exclude '*.html' feedback
grep -R content
adb devices | grep -o '^[a-zA-Z0-9]*'
ls | grep -v PAT
grep
is particularly useful when you stick to plain text.