seek(GWFILE, 0, 1);
This clears the end-of-file condition on the handle, so that the next <GWFILE> makes Perl try again to read something.
If that doesn't work (it relies on features of your stdio implementation), then you need something more like this:
for (;;) {
for ($curpos = tell(GWFILE); <GWFILE>; $curpos = tell(GWFILE
+)) {
# search for some stuff and put it into files
}
# sleep for a while
seek(GWFILE, $curpos, 0); # seek to where we had been
}
If this still doesn't work, look into the POSIX module. POSIX defines the clearerr() method, which can remove the end of file condition on a filehandle. The method: read until end of file, clearerr(), read some more. Lather, rinse, repeat.
There's also a File::Tail module from CPAN.
| [reply]
[d/l]
[select] |
I've used something like this before:
use IO::File;
use strict;
my $tail = new IO::File;
$tail->open("<./log.dat");
while(1){
my @lines=$tail->getlines();
if(0==scalar(@lines)){
# wait 1 second before trying again...
# to keep from hogging CPU cycles
sleep 1;
}else{
my $line;
foreach $line(@lines){
chomp $line;
print " \"$line\"\n";
}
}
}
I've originally wrote this code w/ a select/can_read but it
ended up hogging the CPU so I put in the 1 second sleep.
A few problems with this code:
- Up to a 1 second delay between data being flushed to the log and the program detecting it
- Can't detect EOF, keeps waiting for more data
even after the writing program has closed the
logfile. Of course, tail -f has this same problem.
The program writing to the logfile needs to be flushing
its output or you may get irregular results
(i.e. sometimes partial lines, etc....). | [reply]
[d/l] |
Thanks, this looks like it will do the job nicely for what I need to do.
| [reply] |
The ever-wise Uri Guttman has finally uploaded File::ReadBackwards to the CPAN.
From its description, it looks like what you want. | [reply] |
@log = qx{tail -f $mylogfile};
Updated: leave out the -f (see reply below). I'm sorry I can't do better than that I don't have accces to the man command on my linux box (I'm in work).
Nuance
| [reply]
[d/l] |
Surely that line would not finish until the tail had reached EOF and tail -f doesn't - it just waits for more input
| [reply] |
Sorry Nuance I don't think that would work either, tail on its own will only return n number of records, its the stream itself I want to attach to.
Thanks anyway
| [reply] |