NAME

       clfmerge - merge Common-Log Format web logs based on time-stamps

SYNOPSIS

       clfmerge [--help | -h] [-b size] [-d] [-v] [file names]

DESCRIPTION

       The clfmerge program is designed to avoid using sort to merge multiple web log files.  Web
       logs for big sites consist of multiple files in the >100M size  range  from  a  number  of
       machines.   For  such  files it is not practical to use a program such as gnusort to merge
       the files because the data is not always entirely in order (so the merge option of gnusort
       doesn't  work so well), but it is not in random order (so doing a complete sort would be a
       waste).  Also the date field that is being sorted on is not particularly easy  to  specify
       for gnusort (I have seen it done but it was messy).

       This  program is designed to simply and quickly sort multiple large log files with no need
       for temporary storage space or overly large buffers in memory  (the  memory  footprint  is
       generally only a few megs).

OVERVIEW

       It  will  take a number (from 0 to n) of file-names on the command line, it will open them
       for reading and read CLF format web log data from them all.  Lines which don't  appear  to
       be  in CLF format (NB they aren't parsed fully, only minimal parsing to determine the date
       is performed) will be rejected and displayed on standard-error.

       If zero files are specified then there will be no error,  it  will  just  silently  output
       nothing,  this is for scripts which use the find command to find log files and which can't
       be counted on to find any log files, it saves doing an extra check in your shell scripts.

       If one file is specified then the data will be read into a 1000 line buffer and it will be
       removed  from  the  buffer  (and  displayed on standard output) in date order.  This is to
       handle the case of web servers which date entries on the connection time but write them to
       the  log at completion time and thus generate log files that aren't in order (Netscape web
       server does this - I haven't checked what other web servers do).

       If more than one file is specified then a line will be read from each file, the file  that
       had the earliest time stamp will be read from until it returns a time stamp later than one
       of the other files.  Then the file with  the  earlier  time  stamp  will  be  read.   With
       multiple  files  the  buffer size is 1000 lines or 100 * the number of files (whichever is
       larger).  When the buffer becomes full the first line will be  removed  and  displayed  on
       standard output.

OPTIONS

       -b buffer-size
              Specify  the  buffer-size  to  use,  if 0 is specified then it means to disable the
              sliding-window sorting of the data which improves the speed.

       -d     Set domain-name mangling to on.  This means that if a line starts with as the  name
              of  the  site  that  was requested then that would be removed from the start of the
              line and the GET / would be changed to  GET  http://www.company.com/  which  allows
              programs  like  Webalizer  to produce good graphs for large hosting sites.  Also it
              will make the domain name in lower case.

       -v     Be more verbose.

EXIT STATUS

       0 No errors

       1 Bad parameters

       2 Can't open one of the specified files

       3 Can't write to output

AUTHOR

       This program, its manual page, and the  Debian  package  were  written  by  Russell  Coker
       <russell@coker.com.au>.

SEE ALSO

       clfsplit(1),clfdomainsplit(1)