conditional statement with awk - linux

Question

I'm new with linux
I'm trying to get logs between two dates with gawk.
this is my log
Oct 07 11:00:33 abcd
Oct 08 12:00:33 abcd
Oct 09 14:00:33 abcd
Oct 10 21:00:33 abcd
I can do it when both start and end date are sent
but I have problem when start or end date or both are not sent
and I don't know how to check it .
I've written below code but it has syntax error .
sudo gawk -v year='2022' -v start='' -v end='2022:10:08 21:00:34' '
BEGIN{ gsub(/[:-]/," ", start); gsub(/[:-]/," ", end) }
{ dt=year" "$1" "$2" "$3; gsub(/[:-]/," ", dt) }
if(start && end){mktime(dt)>=mktime(start) && mktime(dt)<=mktime(end)}
else if(end){mktime(dt)<=mktime(end)}
else if(start){mktime(dt)>=mktime(start)} ' log.txt
How can I modify this code ?

Answer 1

I'd write:
gawk -v end="Oct 10 12:00:00" '
function to_epoch(timestamp, n, a) {
n = split(timestamp, a, /[ :]/)
return mktime(strftime("%Y", systime()) " " month[a[1]] " " a[2] " " a[3] " " a[4] " " a[5])
}
BEGIN {
split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec", m)
for (i=1; i<=12; i++) month[m[i]]=i
if (start) {_start = to_epoch(start)} else {_start = 0}
if (end) {_end = to_epoch(end)} else {_end = 2**31}
}
{ ts = to_epoch($0) }
_start <= ts && ts <= _end
' log.txt
You'll pass the start and/or end variables with the same datetime format as appears in the log file.

Answer 2

This would be easier with dateutils, e.g.:
<infile dategrep -i '%b %d %H:%M:%S' '>Oct 08 00:00:00' |
dategrep -i '%b %d %H:%M:%S' '<Oct 09 23:59:59'
Output:
Oct 08 12:00:33 abcd
Oct 09 14:00:33 abcd