Programming Perl, 4th Edition

write

write FILEHANDLE
write

This function writes a formatted record (possibly multiline) to the specified filehandle, using the format associated with that filehandle—see the section Format Variables in Chapter 26. By default, the format associated with a filehandle is the one having the same name as the filehandle. However, the format for a filehandle may be changed by altering the $~ variable after you select that handle:

$old_fh = select(HANDLE);
$~ = "NEWNAME";
select($old_fh);

or by saying:

use IO::Handle;
HANDLE–>format_name("NEWNAME");

Since formats are put into a package namespace, you may have to fully qualify the format name if the format was declared in a different package:

$~ = "OtherPack::NEWNAME";

Top-of-form processing is handled automatically. If there is insufficient room on the current page for the formatted record, the page is advanced by writing a form feed, a special top-of-page format is used for the new page header, and then the record is written. The number of lines remaining on the current page is in the variable $–, which can be set to 0 to force a new page on the next write. (You may need to select the filehandle first.) By default, the name of the top-of-page ...