Returns the current position in bytes for FILEHANDLE, or -1 on error. FILEHANDLE may be an expression whose value gives the name of the actual filehandle. If FILEHANDLE is omitted, assumes the file last read.
Note the emphasis on bytes: even if the filehandle has been set to operate on characters (for example using the
:encoding(UTF-8) I/O layer), the
sysseek family of functions use byte offsets, not character offsets, because seeking to a character offset would be very slow in a UTF-8 file.
The return value of
tell for the standard streams like the STDIN depends on the operating system: it may return -1 or something else.
tell on pipes, fifos, and sockets usually returns -1.
There is no
systell function. Use
sysseek($fh, 0, 1) for that.
Do not use
tell (or other buffered I/O operations) on a filehandle that has been manipulated by
sysseek. Those functions ignore the buffering, while
tell does not.