FAQ 6.4 I put a regular expression into $/ but it didn't work. What's wrong?

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6.4: I put a regular expression into $/ but it didn't work. What's wrong?

    Up to Perl 5.8.0, $/ has to be a string. This may change in 5.10, but
    don't get your hopes up. Until then, you can use these examples if you
    really need to do this.

    If you have File::Stream, this is easy.

                             use File::Stream;
                 my $stream = File::Stream->new(
                      separator => qr/\s*,\s*/,

                             print "$_\n" while <$stream>;

    If you don't have File::Stream, you have to do a little more work.

    You can use the four argument form of sysread to continually add to a
    buffer. After you add to the buffer, you check if you have a complete
    line (using your regular expression).

           local $_ = "";
           while( sysread FH, $_, 8192, length ) {
              while( s/^((?s).*?)your_pattern/ ) {
                 my $record = $1;
                 # do stuff here.

     You can do the same thing with foreach and a match using the
     c flag and the \G anchor, if you do not mind your entire file
     being in memory at the end.

           local $_ = "";
           while( sysread FH, $_, 8192, length ) {
              foreach my $record ( m/\G((?s).*?)your_pattern/gc ) {
                 # do stuff here.
              substr( $_, 0, pos ) = "" if pos;


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