How do I read a file which is constantly updating?

Question

I am getting a stream of data (text format) from an external server and like to pass it on to a script line-by-line. The file is getting appended in a continuous manner. Whi

Answer 1

In perl there are a couple of modules that make tailing a file easier. IO::Tail and File::Tail one uses a callback the other uses a blocking read so it just depends on which suits your needs better. There are likely other tailing modules as well but these are the two that came to mind.

IO::Tail - follow the tail of files/stream

 use IO::Tail;
 my $tail = IO::Tail->new();
 $tail->add('test.log', \&callback);
 $tail->check();
 $tail->loop();

File::Tail - Perl extension for reading from continously updated files

use File::Tail;
my $file = File::Tail->new("/some/log/file");
while (defined(my $line= $file->read)) {
    print $line;
}