open (FILEHANDLE,"file.txt") ;
@data = <FILEHANDLE> ;
close (FILEHANDLE) ;
chomp(@data); ## this will cut off the \n or \r
              ## in the end of each line.

##</code><code>##

open (FILEHANDLE,"file.txt") ;
my $data ;
1 while( read(FILEHANDLE, $data , 1024*8 , length($data) ) ) ;
close (FILEHANDLE) ;

##</code><code>##

open (FILEHANDLE,"file.txt") ;
while ($line = <FILEHANDLE>) { ... }
close (FILEHANDLE) ;

##</code><code>##

open (FILEHANDLE,"file.txt") ;
binmode(FILEHANDLE) ;

##</code><code>##

$line .= $_

##</code><code>##

$var += 10 ; # $var = $var + 10 ;
$var -= 10 ; # $var = $var - 10 ;
$var *= 10 ; # $var = $var * 10 ;
$var /= 10 ; # $var = $var / 10 ;