我试图了解使用之间的区别：
grep [^klm]fair - This matches any single character not in the string ‘klm’ - k or lm or km - followed by any string that has the text ‘fair’ in it
grep [kl^m]fair - I am not sure what this means. I want to assume that it means - matches any single character in string which includes k,l NOT m, followed by any string that has the text 'fair' in it....
对吗？