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Top Forums Shell Programming and Scripting To check if a file is open and in use (logs are being written to it) Post 302957592 by Scrutinizer on Tuesday 13th of October 2015 06:17:28 AM
Old 10-13-2015
Your loop constantly closes and opens the output file for append, so whether you see something with lsof becomes a race condition.

Instead try:
Code:
while true; do echo `date` ; done >abc.txt

or to append:
Code:
while true; do echo `date` ; done >>abc.txt

In both cases the output file is opened once and kept open the whole time for the duration of the loop.

Last edited by Scrutinizer; 10-13-2015 at 07:23 AM..
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IO::Async::Timer::Absolute(3pm) 			User Contributed Perl Documentation			   IO::Async::Timer::Absolute(3pm)

NAME
"IO::Async::Timer::Absolute" - event callback at a fixed future time SYNOPSIS
use IO::Async::Timer::Absolute; use POSIX qw( mktime ); use IO::Async::Loop; my $loop = IO::Async::Loop->new; my @time = gmtime; my $timer = IO::Async::Timer::Absolute->new( time => mktime( 0, 0, 0, $time[4]+1, $time[5], $time[6] ), on_expire => sub { print "It's midnight "; $loop->stop; }, ); $loop->add( $timer ); $loop->run; DESCRIPTION
This subclass of IO::Async::Timer implements one-shot events at a fixed time in the future. The object waits for a given timestamp, and invokes its callback at that point in the future. For a "Timer" object that waits for a delay relative to the time it is started, see instead IO::Async::Timer::Countdown. EVENTS
The following events are invoked, either using subclass methods or CODE references in parameters: on_expire Invoked when the timer expires. PARAMETERS
The following named parameters may be passed to "new" or "configure": on_expire => CODE CODE reference for the "on_expire" event. time => NUM The epoch time at which the timer will expire. Once constructed, the timer object will need to be added to the "Loop" before it will work. Unlike other timers, it does not make sense to "start" this object, because its expiry time is absolute, and not relative to the time it is started. AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-10-24 IO::Async::Timer::Absolute(3pm)
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