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How do I tail -f a file if it is NFS mounted?

by tim (Initiate)
on Sep 05, 2000 at 23:08 UTC ( #31158=categorized question: print w/replies, xml ) Need Help??
Contributed by tim on Sep 05, 2000 at 23:08 UTC
Q&A  > files


The standard answers to this question, found in the FAQ and in the perl cookbook, don't seem to be working. I'd like to avoid a tell-close-open-seek series of calls, as it seems that would add a lot of overhead.

Answer: How do I tail -f a file if it is NFS mounted?
contributed by lhoward

I've used this technique before with quite a bit of success. Only problem is that it can't detect a "real" EOF (writer has stopped writing to the file) but that will be the case with just about any method:

#!/usr/bin/perl -w 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"; } } }
Answer: How do I tail -f a file if it is NFS mounted?
contributed by merlyn

I would use File::Tail.

Answer: How do I tail -f a file if it is NFS mounted?
contributed by tim

Whoops :( My implementation of the example found in "perldoc -f seek" was incomplete. This one seems to work:

for (;;) { for ($curpos = tell(FILE); $_ = <FILE>; $curpos = tell(FILE)) { # search for some stuff and put it into files } sleep($for_a_while); seek(FILE, $curpos, 0); }
I'm really not that much of an idiot. really.

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