I generally cheat for things like this: if you're on Unix, just run tail -f filename through a pipe and select on the resulting fileno. Here's a snippet from wikimon, a script I wrote to IM me whenever someone edits a page on my work wiki: 
# Recent changes log
my $RC_FILE = "$TOPDIR/wikidb/rclog";
open(TAIL, "tail -f -n 0 $RC_FILE |");

my $rin = '';
vec($rin, fileno(TAIL), 1) = 1;
while (1) {
  # Check for file input
  select(my $rout = $rin, undef, undef, undef);
  if (vec($rout, fileno(TAIL), 1)) {
    ...;
  }
}

[download]
Actually, the original uses a select timeout of zero, because I'm also waiting for IM commands to come in, so I do a nonblocking poll and then a timed wait on the IM stuff (it doesn't expose file descriptors to select on).

In reply to Re: blocking, non-blocking, and semi-blocking by sfink
in thread blocking, non-blocking, and semi-blocking by genecutl

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