I was doing some everyday grepping and suddenly discovered that something seemingly trivial does not work:
$ echo T | grep [A-Z]
No match.
How come T is not within A-Z range?
I changed the regex a tiny bit:
$ echo T | grep [A-Y]
A match!
Whoa! How is T within A-Y but not within A-Z?
Apparently this is because my environment is set to Estonian locale where Y is at the end of the alphabet but Z is somewhere in the middle: ABCDEFGHIJKLMNOPQRSŠZŽTUVWÕÄÖÜXY
$ echo $LANG
et_EE.UTF-8
This all came as a bit of a shock to me. 99% of the time I grep computer code, not Estonian literature. Have I been using grep the wrong way all the time? What all kind of mistakes have I made because of this in the past?
After trying several things I arrived at the following solution:
$ echo T | LANG=C grep [A-Z]
Is this the recommended way to make grep locale-independent?
Further more... would it be safe to define an alias like that:
$ alias grep="LANG=C grep"
PS. I'm also wondering of why are the character ranges like [A-Z] locale dependent in the first place while \w seems to be unaffected by locale (although the manual says \w is equivalent of [[:alnum:]] - but I found out the latter depends on locale while \w does not).