Shell Programming and Scripting

Hi all

I wrote this, and am very new to PERL. Could someone show me what i might be doing wrong?? Here is my code:

open(DATA1,"ping1.txt");
open(DATA2,"ping2.txt");

$data1 = <DATA1>;
$data2 = <DATA2>;

while ($data1 || $data2) {
next if !strcmp($data1,$data2);
print "<DATA1";
print ">DATA2";

$data1= <DATA1>;
$data2= <DATA2>;

}

basically, i am running a ping and putting the results into a file. What I want to do is compare the 2 largest files and annotate the differences (if any)

the error i get is: undefined subroutine &main::strcmp called at filename.pl <DATA2> chunk1

SO I thought, hmm subroutine. So I tried declaring one before the next if before the { but I received even more errors.

But now I am lost...can anyone provide me some help?

Thanks

Joe

Unlike C, perl does not have a function called strcmp. To compare two strings, you just have to do this:

Code:

if($data1==$data2) {
--do whatever you want here--
}
else {
--do something else here--
}

strcmp in perl is

if( $data1 eq $data2 ){

}else{

}

Interesting, I sorta found that out, but at first I was using != for not equal. Error city. Anyway, so that is how my script looks. However, all that is output now is

<
>
<
>
<
>

Here is what my script looks like now:

open(DATA1,"ping1.txt");
open(DATA2,"ping2.txt");

$data1 = <DATA1>;
$data2 = <DATA2>;

while ($data1 || $data2) {
if ($data1 ne $data2) {

else print "<$data1";
print ">$data2";
}

$data1= <DATA1>;
$data2= <DATA2>;

}

Like I said, all i get now is
<
>
<
>
in a repeating pattern that never ends. Should I put an EOF in there somewhere? Another question is I KNOW the files are different because i made some changes to test them

I know I am overlooking something here...

Thank You for your inputs.

Joe

Your code seems to work for me with slight modifications, but give me some weird results at the end.

Try chomping the lines retrieved first before throwing to while {}, and unlike C/Java you always need the braces for blocks like if-else/for even if the block consists of only one statement. This is likely to work better I think:

Code:

open(DATA1,"ping1.txt");
open(DATA2,"ping2.txt");
 
chomp( $data1 = <DATA1>);
chomp( $data2 = <DATA2>);
 
while ($data1 || $data2) {
   if ($data1 ne $data2) {
       print "<$data1\n";
       print ">$data2\n";
   }
 
   chomp($data1= <DATA1>);
   chomp($data2= <DATA2>);
 
 }

Thanks!! That works perfectly.

Yes, I am new to perl..lol similar to C but different at the same time.

In shell, you can use diff instead.

diff is so powerful.

relative cmd like : paste, comm, join ....