Please explain: print <<"END

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

I'm reading someone else's code and came across this code:

sub usage() 
{
    print <<"END_USAGE";

Usage: -f <file>

END_USAGE
}
[download]

This is used in conjunction with GetOpt::Long so I'm wondering how that print syntax works. Is it something specific to GetOpt or what? I couldn't find any mention of it in the perldoc page for GetOpt::Long. Thanks.

Comment on Please explain: print <<"END_USAGE"; Select or Download Code

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Re: Please explain: print <<"END_USAGE"; by Fletch (Bishop) on Feb 15, 2008 at 18:01 UTC
Because it's a here-doc which has nothing to do with Getopt::Long specifically. Search for "<<EOF" in perlop in the section on quote-like operators, but basically it means create a string from everything following this line up to the next line beginning with the terminator string given after the "<<". The cake is a lie. The cake is a lie. The cake is a lie.	[reply]
Re^2: Please explain: print <<"END_USAGE"; by richz (Beadle) on Feb 15, 2008 at 18:17 UTC
Thanks, it was hard finding help searching for `print <<`, but now I know where to look!	[reply] [d/l]
Re^3: Please explain: print <<"END_USAGE"; by ikegami (Patriarch) on Feb 15, 2008 at 18:25 UTC
Cause it has nothing to do with `print`. `my ($var1, $var2) = (<<'EOI', <<'EOI'); ... EOI ... EOI` [download]	[reply] [d/l] [select]