my $SrcFile   = $ARGV[0] || "users.imp"; 
my $Ext       = 'imp'; 
my $CurLetter = "\0"; 
my $line; 
my %FN;                                        # File Names 
my %FH;                                        # File Handles 
 
# Open source file. 
open(SRCFILE, "<$SrcFile") or die "Unable to open file $SrcFile\n"; 
print "Working...\n"; 
while ( $line = <SRCFILE> ) { 
    $CurLetter = substr($line, 0, 1); 
    if ( !defined $FN{$CurLetter} ) { 
        $FN{$CurLetter} = "$CurLetter.$Ext"; 
        open($FH{$CurLetter}, ">".$FN{$CurLetter}) or die "Unable to open/create target file\n"; 
    } 
    print {$FH{$CurLetter}} "$line"; 
} 
 
print "Done.\n"; 
# Close all. 
close;