linux/tools/bpf/bpftool/Documentation/bpftool-iter.rst
Quentin Monnet 18841da981 tools: bpftool: Automate generation for "SEE ALSO" sections in man pages
The "SEE ALSO" sections of bpftool's manual pages refer to bpf(2),
bpf-helpers(7), then all existing bpftool man pages (save the current
one).

This leads to nearly-identical lists being duplicated in all manual
pages. Ideally, when a new page is created, all lists should be updated
accordingly, but this has led to omissions and inconsistencies multiple
times in the past.

Let's take it out of the RST files and generate the "SEE ALSO" sections
automatically in the Makefile when generating the man pages. The lists
are not really useful in the RST anyway because all other pages are
available in the same directory.

v3:
- Fix conflict with a previous patchset that introduced RST2MAN_OPTS
  variable passed to rst2man.

v2:
- Use "echo -n" instead of "printf" in Makefile, to avoid any risk of
  passing a format string directly to the command.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910203935.25304-1-quentin@isovalent.com
2020-09-10 20:10:45 -07:00

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============
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