tr: trying to find the right incantation of a character class...

[Olivier Brunel]

On Tue, 29 Aug 2017 19:23:39 +0200 (CEST)
Cristian Ionescu-Idbohrn <cristian.ionescu-idbohrn at axis.com> wrote:

> ...to do this:
> 
> $ echo 'hello world-1' | tr -d '[ -]'
> 
> that is, remove all SPACES (0x20) and dashes (0x2D) in input?  I get 

echo 'hello world-1' | tr -d -- ' -'


> mixed results with both various versions of busybox but also with the 
> coreutils `tr' and the characters order placed in the character class.
> 
> `man 7 regex' is telling us:

SETs in tr(1) aren't actually regex, so this doesn't apply. As shown
above, simply list the characters you wanna delete.

`man tr` tells us:

	SETs  are  specified  as  strings  of characters.  Most
	represent themselves.

HTH,