FAQ 5.5 How can I use Perl's "-i" option from within a program?

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5.5: How can I use Perl's "-i" option from within a program?

    "-i" sets the value of Perl's $^I variable, which in turn affects the
    behavior of "<>"; see perlrun for more details. By modifying the
    appropriate variables directly, you can get the same behavior within a
    larger program. For example:

            # ...
            local($^I, @ARGV) = ('.orig', glob("*.c"));
            while (<>) {
                    if ($. == 1) {
                            print "This line should appear at the top of each
                    s/\b(p)earl\b/erl/i;        # Correct typos, preserving
                    close ARGV if eof;              # Reset $.
            # $^I and @ARGV return to their old values here

    This block modifies all the ".c" files in the current directory, leaving
    a backup of the original data from each file in a new ".c.orig" file.


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