$ echo ABC | awk '$0 ~ /^[a-b]/' ABC $ echo ABC | awk '$0 ~ /^[a-a]/' $ echo ABC | awk '$0 ~ /^a/' $
/a/ doesn't. Why?
It is a "locale" problem, I think.
In my locale, it_IT, the following snippet
the following command shows the collating order in your locale:
the output on my machine is
(cannot understand from bash's manual page if sequence expressions are expanded in locale collating order or not; it seems not).