Writes a formatted record (possibly multi-line) to the specified FILEHANDLE, using the format associated with that file. By default the format for a file is the one having the same name as the filehandle, but the format for the current output channel (see the select function) may be set explicitly by assigning the name of the format to the $~ variable.
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 and a special top-of-page format is used to format the new page header before the record is written. By default, the top-of-page format is the name of the filehandle with _TOP appended, or top in the current package if the former does not exist. This would be a problem with autovivified filehandles, but it may be dynamically set to the format of your choice by assigning the name to the $^ variable while that filehandle is selected. The number of lines remaining on the current page is in variable $-, which can be set to 0 to force a new page.
If FILEHANDLE is unspecified, output goes to the current default output channel, which starts out as STDOUT but may be changed by the select operator. If the FILEHANDLE is an EXPR, then the expression is evaluated and the resulting string is used to look up the name of the FILEHANDLE at run time. For more on formats, see perlform.
Note that write is not the opposite of read. Unfortunately.