=over =item sysseek FILEHANDLE,POSITION,WHENCE X X Sets FILEHANDLE's system position I using L. FILEHANDLE may be an expression whose value gives the name of the filehandle. The values for WHENCE are C to set the new position to POSITION; C to set it to the current position plus POSITION; and C to set it to EOF plus POSITION, typically negative. Note the emphasis on bytes: even if the filehandle has been set to operate on characters (for example using the C<:encoding> I/O layer), the L|/seek FILEHANDLE,POSITION,WHENCE>, L|/tell FILEHANDLE>, and L|/sysseek FILEHANDLE,POSITION,WHENCE> family of functions use byte offsets, not character offsets, because seeking to a character offset would be very slow in a UTF-8 file. L|/sysseek FILEHANDLE,POSITION,WHENCE> bypasses normal buffered IO, so mixing it with reads other than L|/sysread FILEHANDLE,SCALAR,LENGTH,OFFSET> (for example L|/readline EXPR> or L|/read FILEHANDLE,SCALAR,LENGTH,OFFSET>), L|/print FILEHANDLE LIST>, L|/write FILEHANDLE>, L|/seek FILEHANDLE,POSITION,WHENCE>, L|/tell FILEHANDLE>, or L|/eof FILEHANDLE> may cause confusion. For WHENCE, you may also use the constants C, C, and C (start of the file, current position, end of the file) from the L module. Use of the constants is also more portable than relying on 0, 1, and 2. For example to define a "systell" function: use Fcntl 'SEEK_CUR'; sub systell { sysseek($_[0], 0, SEEK_CUR) } Returns the new position, or the undefined value on failure. A position of zero is returned as the string C; thus L|/sysseek FILEHANDLE,POSITION,WHENCE> returns true on success and false on failure, yet you can still easily determine the new position. =back