awk中的MMDDYYYY日期格式比较

Question

I Just started to use Awk . Here I include my awk code which is used for retrieve the names of person who are all born on or before 05171997

awk -F "\t" '(substr($2,5,4)<1997||(substr($2,5,4)==1997 && substr($2,1,2)<=05 && substr($2,3,2)<=17)) {print $1}' <input.txt

Data at the input.txt

Bharath 01061992
Ragul   10302002
Bala    01171993
Arjun   05142003
Vimal   06301997
Ramesh  05171997
Kamal   05151997
Vinoth  05201997

It just fine for Now. I want to know Is there any other best way to compare two dates than my method of comparison?

Answer 1

You can rearrange them into the ISO date format, which can easily be used for arithmetic comparisons.

Assuming you have GNU awk(for gensub).

awk -F'\t' -vdate="19970517" 'date>=gensub(/(....)(....)/,"\\2\\1",1,$2){print $1}' f

produces

Bharath 
Bala    
Ramesh  
Kamal