Reading files and regex, Newb at Perl

[CoffeeFrapp]

I'm trying to write a program that reads the 27th line of a file(chuck), then depending if the line contains a command(hello) then have it print a line(Goodbye). I've tried to find examples of how to do this but its never worked properly. If somebody could just show me how this would work using the things in parenthesis it would greatly be appreciated

 

[feherke]

Hi

I've tried to find examples of how to do this but its never worked properly.

Then show us what you tried to do and how it never worked.

By the way, why this looks like homework ?

Feherke.

http://rootshell.be/~feherke/

 

[rharsh]

What have you tried? Even if it's not working, post some code.

 

[CoffeeFrapp]

It may seem like homework because i have no idea what im doing, and i don't want to look stupid because of how retarded my code looks lol. I've tried a few things including

open(INBOX,'/var/spool/mail/chuck') or die "$!";
$line = 0;
while(<INBOX>) {
if ($line >= 27) {
my $command == $_;
print "$_ success";
} 
else {
print "Failure\n";
}
}

and

open(INBOX,'/var/spool/mail/chuck') or die "No new Email Commands";
 while (<INBOX>) {
chomp($line) if 27 .. 27;
my ($command) = $_;
}

These were just trying to test if i could figure out how to read the file

 

[KevinADC]

open(INBOX,'/var/spool/mail/chuck') or die "$!";
<INBOX> for (1..26);
chomp(my $line 27 = <INBOX>);
if (lc($line) eq 'hello') {
   print "Goodbye\n";
}
else {
   print "Now what?\n";
}
close INBOX;

------------------------------------------
- Kevin, perl coder unexceptional!

 

[KevinADC]

this line:

chomp(my $line 27 = <INBOX>);

should be:

chomp(my $line = <INBOX>);



------------------------------------------
- Kevin, perl coder unexceptional!

 

[CoffeeFrapp]

Thank you that works beautifully. If you were wondering what I'm trying to do is write a program to perform system commands via SMS texts/emails

 

[feherke]

Hi

Anyway, extracting those commands from a mail file by line number sounds like a bad idea.


Feherke.

http://rootshell.be/~feherke/

 

[CoffeeFrapp]

How so? Every time it runs it clears the file, and the message always is on the same line, and if the keyword doesn't match any command it returns an error

 

[feherke]

Hi

Mail files are composed by variable number of header lines, a blank line, then the body. There is no reason to suppose that the number of header lines will be always the same. Even more, header lines may be physically wrapped to multiple lines, or not.

I suppose the command is in the mail body. So better search for separator blank line, and your command will be on next line.

Based on Kevin's code I would do it like this :

[b]open[/b][teal]([/teal]INBOX[teal],[/teal][green][i]'/var/spool/mail/chuck'[/i][/green][teal])[/teal] or [b]die[/b] [green][i]"$!"[/i][/green][teal];[/teal]

[b]do[/b] [teal]{[/teal]
  [b]chomp[/b][teal]([/teal][navy]$line[/navy][teal]=[/teal][green][i]<INBOX>[/i][/green][teal]);[/teal]
[teal]}[/teal] [b]while[/b] [teal]([/teal][navy]$line[/navy] ne [green][i]''[/i][/green][teal]);[/teal]

[b]chomp[/b][teal]([/teal][navy]$line[/navy][teal]=[/teal][green][i]<INBOX>[/i][/green][teal]);[/teal]

[b]if[/b] [teal]([/teal][b]lc[/b][teal]([/teal][navy]$line[/navy][teal])[/teal] [b]eq[/b] [green][i]'hello'[/i][/green][teal])[/teal] [teal]{[/teal]
  [b]print[/b] [green][i]"Goodbye\n"[/i][/green][teal];[/teal]
[teal]}[/teal] [b]else[/b] [teal]{[/teal]
  [b]print[/b] [green][i]"Now what?\n"[/i][/green][teal];[/teal]
[teal]}[/teal]
[b]close[/b] INBOX[teal];[/teal]

Feherke.

http://rootshell.be/~feherke/

 

[KevinADC]

I agree it sounds like a bad idea for a general application but it could work for a specific application.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[rharsh]

I meant to post this earlier - guess I didn't.

You can also look at the $. special variable. It contains the line number from the last filehandle that was read.

 

[stevexff]

If you were wondering what I'm trying to do is write a program to perform system commands via SMS texts/emails

Please tell me this doesn't run as root...

Steve

[small]"Every program can be reduced by one instruction, and every program has at least one bug. Therefore, any program can be reduced to one instruction which doesn't work." (Object:erlDesignPatterns)[/small]