Perl 5 version documentation

tell

Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage
  • tell FILEHANDLE

  • tell

    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 seek, tell, and 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 sysread, syswrite, or sysseek. Those functions ignore the buffering, while tell does not.