UNIX for Dummies Questions & Answers

127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET       /apache_pb.gif HTTP/1.0" 200 2326

awk '{print substr($4,2,17)}' logfile

awk 'substr($4,2,17) == "10/Oct/2000:13:55" && $9 ~ /^[0-9]$*/ && $10 ~ /^[0-9]$*/ {sum += $10}' logfile

function rindex(str,c)
{
  return match(str,"\\" c "[^" c "]*$")? RSTART : 0
}
{
  idx=substr($4, 2, rindex($4, ":")-1)
  a[idx]+=$NF
}
END {
  for(i in a)
    print i " --> " a[i]
}

idx=substr($4, 2, 17)

     match(s,ere)
           Return the position, in characters, numbering from  1,
           in  string s where the extended regular expression ere
           occurs, or zero if it does not occur  at  all.  RSTART
           will  be  set  to  the starting position (which is the
           same as the returned  value),  zero  if  no  match  is
           found;  RLENGTH  will  be  set  to  the  length of the
           matched string, -1 if no match is found.

function rindex(str,c)
{
# pass in the string to search (str) and a character to search for (c).
# function will return either a position of 'c' in string 'str' OR '0' if 'c' isn't in
# 'str'. The regex passed to 'match' goes like this:
# "\\" - literal '\' - have to escape it with '\' to preserve the meaning
# followed by char 'c' - resulting in '\c' - need to escape in case 'c' is one
# of the regex chars, e.g. '(', ')', '|' etc
# "[^" - anything BUT the following chars or ranges
# followed by char 'c'
# "]*$" - closing the char list/range - char list repeated 0 or more times (*)
#             anchored to the end of the line ($).
#
# If 'match' found a passed in char, its position will be stored in the
# interval var RSTART - RSTART will be retirned
# If 'match didn't find a passeed in char, 'match' itself will return '0' - 
# therefore a value of '0' will be retuned by the function.
#
# E.g. match("a|b|c|d", "\|[^|]*$")
# Look into the 'match(s,re) description above for more info.
#
return match(str,"\\" c "[^" c "]*$")? RSTART : 0
}