linux/tools/bpf/bpftool/Documentation/bpftool-iter.rst

============
bpftool-iter
============
-------------------------------------------------------------------------------
tool to create BPF iterators
-------------------------------------------------------------------------------

:Manual section: 8

SYNOPSIS
========

	**bpftool** [*OPTIONS*] **iter** *COMMAND*

	*COMMANDS* := { **pin** | **help** }

ITER COMMANDS
===================

|	**bpftool** **iter pin** *OBJ* *PATH* [**map** *MAP*]
|	**bpftool** **iter help**
|
|	*OBJ* := /a/file/of/bpf_iter_target.o
|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }

DESCRIPTION
===========
	**bpftool iter pin** *OBJ* *PATH* [**map** *MAP*]
		  A bpf iterator combines a kernel iterating of
		  particular kernel data (e.g., tasks, bpf_maps, etc.)
		  and a bpf program called for each kernel data object
		  (e.g., one task, one bpf_map, etc.). User space can
		  *read* kernel iterator output through *read()* syscall.

		  The *pin* command creates a bpf iterator from *OBJ*,
		  and pin it to *PATH*. The *PATH* should be located
		  in *bpffs* mount. It must not contain a dot
		  character ('.'), which is reserved for future extensions
		  of *bpffs*.

		  Map element bpf iterator requires an additional parameter
		  *MAP* so bpf program can iterate over map elements for
		  that map. User can have a bpf program in kernel to run
		  with each map element, do checking, filtering, aggregation,
		  etc. without copying data to user space.

		  User can then *cat PATH* to see the bpf iterator output.

	**bpftool iter help**
		  Print short help message.

OPTIONS
=======
	.. include:: common_options.rst

EXAMPLES
========
**# bpftool iter pin bpf_iter_netlink.o /sys/fs/bpf/my_netlink**

::

   Create a file-based bpf iterator from bpf_iter_netlink.o and pin it
   to /sys/fs/bpf/my_netlink

**# bpftool iter pin bpf_iter_hashmap.o /sys/fs/bpf/my_hashmap map id 20**

::

   Create a file-based bpf iterator from bpf_iter_hashmap.o and map with
   id 20, and pin it to /sys/fs/bpf/my_hashmap