First, well done for using strictures. They are going to help a lot in sorting out problems with your code as you develop it.
Your immediate issue is you need to add my in front of each variable when you first assign a value to it.
However, you have a long way to go to get your code complete. I suspect you haven't any chance to complete it within the time you have available. You should talk to your lecturer/tutor about the help you need.
We can give you some hints, but obviously just providing a solution is not going to help in the long run. Here are a few hints that will help write reliable software using Perl:
- Use indentation to clearly show nested blocks of code
- Use three parameter open and lexical file handles: open my $fIn, '<', $ruleFile or die "Can't open $ruleFile: $!\n";
- Use Perl's built in functions instead of executing command line tools. Perl's functions will work across most operating systems and are generally more robust against changes in the OS and shell.
Update: fixed missing ',' in sample open code - thanks Laurent_R
Premature optimization is the root of all job security
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print "RULE_FILE : $rulefile \n";
At this point in the code, the $rulefile has not been declared (which is done with the my built-in), leading to a compile-time error, and has not been defined or initialized (which is done by assigning a value to it), leading to a run-time error once the compile-time error has been fixed.
Next error (assuming you have added the my function for every new variable):
my $rulesdir = "C:\\Snort\\rules\\*.rules";
This does not define a directory, so that the next code line will not work as expected. If you want to define a directory, you may want to have:
my $rulesdir = "C:\\Snort\\rules\\";
or perhaps simply:
my $rulesdir = "C:/Snort/rules/";
Next issue:
@rulefiles = `ls $rulesdir\/*.rules`;
From looking at your directory paths, you're working on Windows. The ls command is a Unix system command, it will not work under Windows. You should use Perl internal commands rather than system calls whenever possible. Try this:
my $rulesdir = "C:\\Snort\\rules";
my @rulefiles = glob "$ruledir/*.rules";
Another issue (assuming that you have used my and indented your code correctly, as recommended, and straitening a bit the syntax):
for my $rulefile (@rulefiles){
open my $INFILE, "<", $rulefile or die "Can't open $rulefile $!";
my @rules = <$INFILE>;
close $INFILE;
}
Here, I have corrected and/or improved the syntax, but you have a serious algorithmic problem: you are looping over a list of files (@rulefiles) and, each time through the loop, are assigning the contents of the file to @rules, meaning that when you read the content of the second file, you clobber the previous content of @rules (i.e. what you read from the first file), and so on, so that, in fine, you end up with only the content of the last file.
There are several (actually, many) other issues, but at least, I hope this will help you going forward.
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Laurent_R: ...From looking at your directory paths, you're working on Windows. The ls command is a Unix system command, it will not work under Windows. You should use Perl internal commands rather than system calls whenever possible. Try this: ... FWIW, even unix system commands can be available for windows , ls.exe , tar.exe ... not uncommon with perl programmers
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Yes, sure, you're right, it can be available for Windows, but that requires some specific software installation and it is usually not available on a common (or fresh) Windows installation.
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Thanks for pointing out my mistakes!!
About ls being a UNIX tool and not Windows.
I googled and came across a suggestion on some online forum saying that in environmental variables in PATH I must be adding "C:/Windows/System32" and then reboot.
Unsurprisingly, it didn't work!
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I'm not sure just how big each rule file is, but reading in all of the file seems wasteful when you only want the first part. To carry on with Laurent R's example, you could extract the header part in the first loop and save it into an array for processing later:
my @headers;
for my $rulefile (@rulefiles){
open my $INFILE, "<", $rulefile or die "Can't open $rulefile $!";
my $header;
while ( my $line = <$INFILE> ) {
# see if this line contains opening bracket
if ( $line =~ m/\(/ ) {
my $pos = index( $line, '(' );
last unless $pos > 0;
$header .= substr( $line, 0, $pos );
last;
}
else {
$header .= $line;
}
}
close $INFILE;
push( @headers, $header ) if $header;
}
for my $header ( @headers ) {
print "\nHeader:\n$header\n";
# now process the header
}
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Hi, thanks for guiding !!
I'm trying to learn this language but I'm always confused in this part.
for my $rulefile (@rulefiles){
What exactly is the difference betweeen $rulefile and @rulefiles?
I understand that @rulefiles is an array and is actually referring to the assortment of all the ".rule" file in the folder. but what purpose is $rulefile serving?
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for my $rulefile (@rulefiles) {
# ...
}
is a loop that goes over each of the items (file names) in the @rulefiles array, one after the other, assigns it to the $rulefile variable, so that each of the items can be manipulated with the $rulefile variable name within the body of the loop.
This is a simple example of a Perl one-liner using a similar construct:
$ perl -e 'for my $i (1, 4, 3, 2) {
print "$i\n";
}'
1
4
3
2
$
In this example, the $i variable takes successively each value of the list (1, 4, 3, 2) and the body of the loop simply prints $i to the screen.
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So what question is most important to you? | [reply] |