You are suffering from buffering. Here are two fixes: 
use IO::Handle qw( );
STDOUT->autoflush(1);

do {
    sleep(5);
    print "Hello...";
} while(1);

[download]
use IO::Handle qw( );

do {
    STDOUT->flush();
    sleep(5);
    print "Hello...";
} while(1);

[download]

In reply to Re: Troubles with do...while loop and sleep by ikegami
in thread Troubles with do...while loop and sleep by imlepid

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