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3.10. Short Sleeps

3.10.1. Problem

You need to sleep
for less than a second.

3.10.2. Solution

Use the select( ) function, if your system
supports it:

select(undef, undef, undef, $time_to_sleep);

Some systems don''t support a four-argument select.
The Time::HiRes module provides a sleep function that takes a
floating-point number of seconds:

use Time::HiRes qw(sleep);
sleep($time_to_sleep);

3.10.3. Discussion

Here''s an example of select. It''s a simpler
version of the program in Recipe 1.6. Think
of it as your very own 300-baud terminal.

while (<>) {
select(undef, undef, undef, 0.25);
print;
}

Using Time::HiRes, we''d write it as:

use Time::HiRes qw(sleep);
while (<>) {
sleep(0.25);
print;
}

3.10.4. See Also

The documentation for the CPAN modules Time::HiRes and Benchmark; the
sleep and select functions in
perlfunc(1) and Chapter 29 of
Programming Perl; we use the
select function for short sleeps in the
slowcat program in Recipe 1.6