split-logfile

# This script will take a combined Web server access
# log file and break its contents into separate files.
# It assumes that the first field of each line is the
# virtual host identity (put there by "%v"), and that
# the logfiles should be named that+".log" in the current
# directory.
#
# The combined log file is read from stdin. Records read
# will be appended to any existing log files.
#
%is_open = ();

while ($log_line = <STDIN>) {
    #
    # Get the first token from the log record; it's the
    # identity of the virtual host to which the record
    # applies.
    #
    ($vhost) = split (/\s/, $log_line);
    #
    # Normalize the virtual host name to all lowercase.
    # If it's blank, the request was handled by the default
    # server, so supply a default name.  This shouldn't
    # happen, but caution rocks.
    #
    $vhost = lc ($vhost) or "access";
    #
    # if the vhost contains a "/" or "\", it is illegal so just use 
    # the default log to avoid any security issues due if it is interprted
    # as a directory separator.
    if ($vhost =~ m#[/\\]#) { $vhost = "access" }
    #
    # If the log file for this virtual host isn't opened
    # yet, do it now.
    #
    if (! $is_open{$vhost}) {
        open $vhost, ">>${vhost}.log"
            or die ("Can't open ${vhost}.log");
        $is_open{$vhost} = 1;
    }
    #
    # Strip off the first token (which may be null in the
    # case of the default server), and write the edited
    # record to the current log file.
    #
    $log_line =~ s/^\S*\s+//;
    printf $vhost "%s", $log_line;
}
exit 0;