如何使用正则表达式搜索属于某一时间段的日志

我想在大量的日志文件里搜索属于某个时间段日志行出来，每行日志都有时间的，时间格式为YYYY/MM/DD hh:mm:ss,给定的时间段是不定的，可能会跨分钟、跨小时、跨天、跨月，甚至可能跨年。例如要搜索2012/12/25 到2013/01/04这几天里每天12:00 ~ 14:00的日志。如何把这些日志grep出来？

awk 'BEGIN{print mktime("2012 12 25 10 23 10")}' 

mktime(datespec)
                 Turns datespec into a time stamp of the same form as returned by systime().  The datespec is  a  string
                 of  the form YYYY MM DD HH MM SS[ DST].  The contents of the string are six or seven numbers represent-
                 ing respectively the full year including century, the month from 1 to 12, the day of the month  from  1
                 to  31,  the hour of the day from 0 to 23, the minute from 0 to 59, and the second from 0 to 60, and an
                 optional daylight saving flag.  The values of these numbers need not be within  the  ranges  specified;
                 for  example,  an  hour  of  -1  means  1  hour before midnight.  The origin-zero Gregorian calendar is
                 assumed, with year 0 preceding year 1 and year -1 preceding year 0.  The time is assumed to be  in  the
                 local  timezone.   If  the  daylight saving flag is positive, the time is assumed to be daylight saving
                 time; if zero, the time is assumed to be  standard  time;  and  if  negative  (the  default),  mktime()
                 attempts  to  determine  whether daylight saving time is in effect for the specified time.  If datespec
                 does not contain enough elements or if the resulting time is out of range, mktime() returns -1.

awk字符串比较打印就可以吧？

 awk '$1>"date1"&&$1<"date2"{print}'