Perl5 リファレンス

       write FILEHANDLE

       write EXPR

       write   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, a special top-of-page format
               is used to format the new page header, and then
               the record is written.  By default the top-of-page
               format is the name of the filehandle with "_TOP"
               appended, but it may be dynamically set to the
               format of your choice by assigning the name to the
               `$^' variable while the filehandle is selected.
               The number of lines remaining on the current page
               is in variable `$-', 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 the perlform

               Note that write is not the opposite of `read'.