sysread

Synopsis

$n = sysread($fh, $buf, $length);
$n = sysread($fh, $buf, $length, $offset);

Description

Performs an unbuffered read directly from the OS file descriptor.

Reads up to LENGTH bytes from the filehandle into BUFFER using the underlying read(2) system call, bypassing Perl’s buffered I/O layer. When OFFSET is given, data is placed starting at that byte position within the buffer.

Returns the number of bytes actually read (which may be less than LENGTH), 0 at end-of-file, or undef on error (with $! set to the OS errno).

Warning: Do not mix sysread with buffered I/O (read, readline, <>) on the same filehandle.

See also

read, syswrite, sysseek