sleep in infinite loop

my_nihilist has asked for the wisdom of the Perl Monks concerning the following question:

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Re: sleep in infinite loop by olus (Curate) on Mar 13, 2008 at 14:37 UTC
Flush the output: `#!/usr/bin/perl use warnings; use strict; $\| = 1; while (1) { sleep 5; print "interval"; }` [download]	[reply] [d/l]
Re^2: sleep in infinite loop by dsheroh (Monsignor) on Mar 13, 2008 at 14:45 UTC
Ending the line will also force it to display immediately, so `print "interval\n"` will fix this. It's also probably what the OP actually meant to do, unless he wanted to see "intervalintervalinterval..." all the way across the screen.	[reply] [d/l]
Re^2: sleep in infinite loop by Anonymous Monk on Mar 16, 2011 at 12:35 UTC
you are my GOD !!!! I've been trying to do this for two weeks.. Thanks mate.. By the way what does this "flush" thing do and how it helps in rectifying the problem?? Thanks Shamal	[reply]
Re: sleep in infinite loop by moritz (Cardinal) on Mar 13, 2008 at 14:39 UTC
It works, but you don't see the output because the output is line buffered, and you don't print a newline. If you `print "interval\n"` instead it works as expected.	[reply] [d/l]
Re: sleep in infinite loop by Narveson (Chaplain) on Mar 13, 2008 at 15:33 UTC
For what it's worth, you can make your infinite loop condition accomplish something for you: `while (sleep 5) { print "interval\n"; }` [download]	[reply] [d/l]
Re: sleep in infinite loop by my_nihilist (Sexton) on Mar 13, 2008 at 14:44 UTC
olus and moritz are both right. thanx. i presume that is why removing "sleep 5" produces a screenful all at once (i thought my eyes were just slow)	[reply]
Re: sleep in infinite loop by FunkyMonk (Bishop) on Mar 13, 2008 at 23:56 UTC
You can add `$\| = 1` to turn on autoflush, then you'll see each "interval" as you print them.	[reply] [d/l] [select]
Re^2: sleep in infinite loop by Anonymous Monk on Aug 02, 2010 at 09:48 UTC
But how to print it to a file? Even after printing it, the file is of zero byte.	[reply]
Re^3: sleep in infinite loop by dasgar (Priest) on Aug 02, 2010 at 13:41 UTC
Based on the code that you provided, you're not doing anything with any files. Your print statement is only printing to STDOUT (i.e. your monitor). Assuming that you want to print to both your screen and the file, the modifications to your code below should work. `#!/usr/bin/perl use warnings; use strict; my $file = "file.txt"; open(OF,">",$file) \|\| die "Unable to open file '$file': $!\n"; while (1) { sleep 5; print "interval\n"; # prints to screen print OF "interval\n"; # prints to file } close(OF);` [download]	[reply] [d/l]