How to find lines that contain ONLY lowercase using grep

Question

I am new to bash and am learning to use grep.

grep ^[a-z] file.txt will show all the lines that begin with lowercase
grep [a-z] file.txt all lines with lowercase

Can't figure out how to show lines with ALL lowercase, can anyone help?

Answer 1

You can use anchors in your regex for egrep:

egrep '^[[:lower:]]+$' file

This egrep will only find lines that have only lowercase letters in the (not even space is allowed).