I am embarrassed to admit this, but I have never used a regex exclusion
[^...] before. Regular expressions have been a part of my career for as far back as I can remember. I actually thought I had a pretty solid understanding of all the options available. But, exclusions… I somehow missed them.
With this construct we can find everything EXCEPT
<insert pattern match here>, by using the exception
[^...] character class.
Search the string
a for all characters, EXCEPT a, b, c, d, e, f (no match):
jemurray@mbp-2019:~ $ echo "a" | grep '[^abcdef]'
Repeat the same type of search again, this time for the character
z which is not on the exclusion list
[^abcdef]. A match is found:
jemurray@mbp-2019:~ $ echo "z" | grep '[^abcdef]' z