how much info can a variable store?

[gammaman1]

I'm trying to store a large amount of data into a variable, and then ouputting the results to a text file.

open results, ">results";
$test = `execute program that will output`;
print results "$test";
close results;

so now I will have a huge text file named results. But when I run this, the system hangs. Is there a better way of doing this?

thanks,
gammaman1

 

[uida1154]

concerning the first question: as far as I know perl doesn't care about the amount of data, so it will load until the memory is full.

concerning the second question: does the program outputs the data or is it directed to a file?

 

[MikeLacey]

gammaman,

There are a couple of better ways of doing what I think you're trying to do.

If you're just storing the output of some program in a file, you can do it like this:

system('some_program > a_file');

You might well know that already though.

If you need to change the output of some program and then store it in a file, you can do it like this:

open(A_FILE,'>a_file');
open(SOME_PROGRAM,'some_program|');
while(<SOME_PROGRAM>){
[tab]# each line of output is in $_
[tab]# so you can change it as you go
[tab]# or just write it to the output file like this
[tab]print A_FILE $_;
}
close(SOME_PROGRAM);
close(A_FILE);

Does that help you?

Mike

You cannot really appreciate Dilbert unless you've read it in the
original Klingon.

Want great answers to your Tek-Tips questions? Have a look at faq219-2884

 

[gammaman1]

Thanks for the replies; They've given me more ideas. The problem is that the PERL program I'm writing has to run on windows XP. I have a windows version of grep installed. So what I'm trying to do is this:

1. run the program
2. pipe the results into a grep
3. then pipe that result into another grep
4. now output the results

Unfortunately, windows doesn't seem to have piping, so I was thinking of outputing the results into seperate files to run grep on. Any ideas or approaches to solving this would be much appriciated

thanks,
gammaman1

 

[chazoid]

why do you say piping doesn't work in windows? Windows also actually has a grep-like program with crude regex support called "findstr.exe" I would probably use Mike's method though.

c:\>dir c:\Perl\bin | findstr -i perl

 

[gammaman1]

wow, windows has grep? I never heard of findstr before.
Anyways, I tried Mike's solution, and it seems to work fine if I use a program with little output. But when I do it for the program I'm using, cleartool, it outputs this error message:

grep: writing output: Invalid argument

I tried looking for this on Google but didn't find anything. Any ideas?

thanks,
gammaman1

 

[MikeLacey]

Gammaman,

Use the pattern matching (regular expressions) built into Perl.

You can say things like:

if(/current line matches this text/){
print "matches\n";
} else {
print "doesn't match\n";
}

You should probably replace "current line matches this text" with whatever you need to though


Mike

You cannot really appreciate Dilbert unless you've read it in the
original Klingon.

Want great answers to your Tek-Tips questions? Have a look at faq219-2884