It's an idiomatic way of turning off output buffering, as controlled by the $| variable. See. perlvar and Perl Idioms Explained - $|++ for more info.
HTH

_________
broquaint

update: s/on/off/, thanks to halley for spotting that

In reply to Re: What the heck does $|++; do? by broquaint
in thread What the heck does $|++; do? by Anonymous Monk

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