CONFIG_TULIP_NAP => y
CONFIG_USB_SISUSBVGA_CO => y
CONFIG_PC30 => m
CONFIG_USB_TES => m
CONFIG_I2C_NFORCE => m
CONFIG_MTD_SBC_GX => m
CONFIG_NTFS_DEBUG => Z
CONFIG_DRM_SI => m
CONFIG_SCSI_ISCSI_ATTR => m
CONFIG_ACPI_SLEE => y
CONFIG_DLCI_MA => 8
CONFIG_SCSI_IPR_DUMP => Z
CONFIG_ECONET_NATIV => y
CONFIG_BRIDG => m
CONFIG_IP_ADVANCED_ROUTE => y
CONFIG_AIC79XX_REG_PRETTY_PRIN => y
CONFIG_IF => m


some of the keys are chopped off 

like CONFIG_BRIDG

there are so many entries in the config file 
with this name.
CONFIG_BRIDGE_NF_EBTABLES=m
CONFIG_BRIDGE_EBT_BROUTE=m
CONFIG_BRIDGE_EBT_T_FILTER=m
CONFIG_BRIDGE_EBT_T_NAT=m
CONFIG_BRIDGE_EBT_802_3=m
CONFIG_BRIDGE_EBT_AMONG=m
CONFIG_BRIDGE_EBT_ARP=m
CONFIG_BRIDGE_EBT_IP=m
CONFIG_BRIDGE_EBT_LIMIT=m
CONFIG_BRIDGE_EBT_MARK=m
CONFIG_BRIDGE_EBT_PKTTYPE=m
CONFIG_BRIDGE_EBT_STP=m
CONFIG_BRIDGE_EBT_VLAN=m
CONFIG_BRIDGE_EBT_ARPREPLY=m
CONFIG_BRIDGE_EBT_DNAT=m
CONFIG_BRIDGE_EBT_MARK_T=m
CONFIG_BRIDGE_EBT_REDIRECT=m
CONFIG_BRIDGE_EBT_SNAT=m
CONFIG_BRIDGE_EBT_LOG=m
CONFIG_BRIDGE_EBT_ULOG=m


similarly,

CONFIG_AIC79XX_REG_PRETTY_PRINT=y

is shown only as 

CONFIG_AIC79XX_REG_PRETTY_PRIN => y

I am maintaining hash with configuration name as
key and value to be y,m,Z

I am puzzled as to why the some keys are getting chopped off
while others are not ?


======
code =>

#!/usr/bin/perl


# This part of the script takes the old config
# file and sets only those options into the new
# config files which are set.


open CONF1 ,"<","config-2.6.18-custom" or die $!;
open CONF2 ,"<","config-2.6.16.27-custom" or die $!;

my @lines1= <CONF1>;
my @lines2= <CONF2>;

sub trim{
   my $string = shift;
   $string =~ s/^\s+|\s+$//g;
   return $string;
}

sub get_config_info_in_mem
{
   my %hash_config = ();
   my ($lref)  = @_;
   my (@lines) = @$lref;

   for $line (@lines)
   {
      if (substr($line,0,6) eq "CONFIG" )
      {
         $i=index($line,"=");
         $val=substr($line,$i+1,length($line)-1-$i);
         $conf=substr($line,0,$i-1);
#      print "$conf=$val\n";
         $conf=trim($conf);
         $val=trim($val);
         $hash_config{$conf} = $val;
      }
      else
      {
         if(substr($line,0,8) eq "# CONFIG")
         {
            $i=index($line,"CONFIG_");
            $i_space=index($line," ",$i+1);
            $conf=substr($line,$i,$i_space-$i);
            $val="Z";
#      print "$conf=$val\n";
            $conf=trim($conf);
            $val=trim($val);
            $hash_config{$conf} = $val;
         }
      }
   }
   return %hash_config;
}

sub print_hash_in_mem
{
   my ($hc) = @_;
   my %hash_config =%$hc;
   while( my($conf,$val) = each(%hash_config))
   {
           print "$conf => $val\n";
   }
}


my %hash_config1=get_config_info_in_mem(\@lines1);
#print $hash_config1."\n";
print_hash_in_mem(\%hash_config1);
# my $hash_config2=get_config_info_in_mem(@lines2);
# print_hash_in_mem(%hash_config2);