perl

What is the relationship between $FILE and FILE?

I found this old Perl code in an old unix book and was surprised it works. What is the relationship between $FILE and FILE in the code below?

#! /usr/bin/env perl

print 'Enter filename: ';
chomp($FILE = <STDIN>);

open(FILE); # what is going on here?

while (<FILE>) {
    print;
}

close(FILE);

exit(0);
Solution

  • open has several different tricks depending on the number of arguments you give it. In the one-argument case such as open(FILE), Perl will take the filename from the scalar package variable with the same name as the bareword filehandle. In this case, using only FILE causes Perl to look in $FILE. See Calling open with one argument via global variables.

    This fell out of favor for several reasons, including: