```{index} single: FileHandle ``` # FileHandle supply object methods for filehandles ## SYNOPSIS ```perl use FileHandle; my $fh = FileHandle->new; if ($fh->open("< file")) { print <$fh>; $fh->close; } my $fh = FileHandle->new("> FOO"); if (defined $fh) { print $fh "bar\n"; $fh->close; } my $fh = FileHandle->new("file", "r"); if (defined $fh) { print <$fh>; undef $fh; # automatically closes the file } my $fh = FileHandle->new("file", O_WRONLY|O_APPEND); if (defined $fh) { print $fh "corge\n"; undef $fh; # automatically closes the file } my $pos = $fh->getpos; $fh->setpos($pos); $fh->setvbuf(my $buffer_var, _IOLBF, 1024); my ($readfh, $writefh) = FileHandle::pipe; autoflush STDOUT 1; ``` ## DESCRIPTION NOTE: This class is now a front-end to the IO::\* classes. `FileHandle::new` creates a `FileHandle`, which is a reference to a newly created symbol (see the [Symbol](Symbol.md) package). If it receives any parameters, they are passed to `FileHandle::open`; if the open fails, the `FileHandle` object is destroyed. Otherwise, it is returned to the caller. `FileHandle::new_from_fd` creates a `FileHandle` like `new` does. It requires two parameters, which are passed to `FileHandle::fdopen`; if the fdopen fails, the `FileHandle` object is destroyed. Otherwise, it is returned to the caller. `FileHandle::open` accepts one parameter or two. With one parameter, it is just a front end for the built-in `open` function. With two parameters, the first parameter is a filename that may include whitespace or other special characters, and the second parameter is the open mode, optionally followed by a file permission value. If `FileHandle::open` receives a Perl mode string (">", "+<", etc.) or a POSIX fopen() mode string ("w", "r+", etc.), it uses the basic Perl `open` operator. If `FileHandle::open` is given a numeric mode, it passes that mode and the optional permissions value to the Perl `sysopen` operator. For convenience, `FileHandle::import` tries to import the O\_XXX constants from the Fcntl module. If dynamic loading is not available, this may fail, but the rest of FileHandle will still work. `FileHandle::fdopen` is like `open` except that its first parameter is not a filename but rather a file handle name, a FileHandle object, or a file descriptor number. If the C functions fgetpos() and fsetpos() are available, then `FileHandle::getpos` returns an opaque value that represents the current position of the FileHandle, and `FileHandle::setpos` uses that value to return to a previously visited position. If the C function setvbuf() is available, then `FileHandle::setvbuf` sets the buffering policy for the FileHandle. The calling sequence for the Perl function is the same as its C counterpart, including the macros `_IOFBF`, `_IOLBF`, and `_IONBF`, except that the buffer parameter specifies a scalar variable to use as a buffer. WARNING: A variable used as a buffer by `FileHandle::setvbuf` must not be modified in any way until the FileHandle is closed or until `FileHandle::setvbuf` is called again, or memory corruption may result! See [perlfunc](core/perlfunc.md) for complete descriptions of each of the following supported `FileHandle` methods, which are just front ends for the corresponding built-in functions: ```text close fileno getc gets eof clearerr seek tell ``` See [perlvar](core/perlvar.md) for complete descriptions of each of the following supported `FileHandle` methods: ```text autoflush output_field_separator output_record_separator input_record_separator input_line_number format_page_number format_lines_per_page format_lines_left format_name format_top_name format_line_break_characters format_formfeed ``` Furthermore, for doing normal I/O you might need these: - $fh->print See ["print" in perlfunc](core/perlfunc/print.md). - $fh->printf See ["printf" in perlfunc](core/perlfunc/printf.md). - $fh->getline This works like <$fh> described in ["I/O Operators" in perlop](core/perlop.md) except that it's more readable and can be safely called in a list context but still returns just one line. - $fh->getlines This works like <$fh> when called in a list context to read all the remaining lines in a file, except that it's more readable. It will also croak() if accidentally called in a scalar context. There are many other functions available since FileHandle is descended from IO::File, IO::Seekable, and IO::Handle. Please see those respective pages for documentation on more functions. ## SEE ALSO The **IO** extension, [perlfunc](core/perlfunc.md), ["I/O Operators" in perlop](core/perlop.md).