Is there a way to always put NA before (or after) numerical values in sort?

[Peng Yu]

Hi,

I want to always put NA before (or after) numerical values being
sorted. Is there a way to control this? Thanks.

~$ printf '%s\n' .1 1 NA | sort -k 1,1rg
1
.1
NA
~$ printf '%s\n' .1 1 NA | sort -k 1,1g
NA
.1
1

-- 
Regards,
Peng