You can in this case, but you should just forget about doing that. The general rule is: you cannot alter files. Learn the four step process posted above.

After you learn to manually do the 4-step process, then you can use a shortcut for that process that perl provides:

use strict;
use warnings;
use 5.010;

use English;

{
    #Turn on inplace editing for <> operator, no backup file:
    local $INPLACE_EDIT = "";  
   
    local @ARGV = "./test/data.txt"; 
    #...or list file name on command line

    while(my $line = <>) {
        $line =~ s/hello/goodbye/;   #alter the line
        print $line;  #...then print() it (*required*)
        
    }
}
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