---
name: sysseek
status: documented
runtime: pp
source: src/runtime/pp/fileio.rs
---
```{index} single: sysseek; Perl built-in (pp runtime)
```

# sysseek

## Synopsis

```perl
$pos = sysseek($fh, $offset, SEEK_SET);  # absolute
$pos = sysseek($fh, 0, SEEK_CUR);        # query position
$pos = sysseek($fh, 0, SEEK_END);        # query file size
```

## Description

Repositions the OS file pointer, bypassing Perl's buffered I/O layer.

Calls `lseek(2)` on the underlying file descriptor to reposition the
read/write offset. Unlike `seek`, this operates at the system-call
level and does not interact with Perl's I/O buffering.

Returns the resulting absolute position (as a "0 but true" string when
the position is zero, per perl5 convention), or `undef` on error (with
`$!` set).

**Warning**: Do not mix `sysseek` with buffered I/O (`seek`, `tell`)
on the same filehandle.

## See also

seek, tell, sysread, syswrite