Here for you:
#!/bin/bash
EDATE=$(tail -1 aa.log | awk '{ print substr($4, 2, length($4)) }')
EEPOCH=$(date -d "$(echo "$EDATE" | awk 'BEGIN { FS = "[/:]"; } \
{ print $1" "$2" "$3" "$4":"$5":"$6 }')" +%s)
time=$(expr 60 \* 60 \* 24 \* 5)
SEPOCH=$(expr $EEPOCH - $time)
while read line
do
DATE=$(echo $line | awk '{ print substr($4, 2, length($4)-1) }' | \
awk 'BEGIN { FS = "[/:]"; } { print $1" "$2" "$3" "$4":"$5":"$6 }')
DEPOCH=$(date -d "$DATE" +%s)
[[ $DEPOCH -ge $SEPOCH && $DEPOCH -le $EEPOCH ]] && echo $line | \
awk '{ print substr($4, 2, length($4)) }' >> as1
done < aa.log
UPDATE
The input:
213.46.27.204 - - [21/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [22/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [23/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [24/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [25/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [26/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [27/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [28/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [29/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [30/Dec/2002:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
213.46.27.204 - - [01/Jan/2003:12:55:21 +0100] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 - "" ""
The output:
$ ./five_last_days.sh
27/Dec/2002:12:55:21
28/Dec/2002:12:55:21
29/Dec/2002:12:55:21
30/Dec/2002:12:55:21
01/Jan/2003:12:55:21