On 26/10/16 17:15, Paul Eggert wrote: > There's no bug here: "expr E" exits with status 1 if E evaluates to 0, > and expressions like "0 : '\([0-9]\)$'" do evaluate to 0.
Yes this is not a bug but is very confusing. I've updated with this specific example at: http://www.pixelbeat.org/docs/coreutils-gotchas.html#expr
