1BPFTOOL-LINK(8)                                                BPFTOOL-LINK(8)
2
3
4

NAME

6       bpftool-link  -  tool  for  inspection  and simple manipulation of eBPF
7       links
8

SYNOPSIS

10          bpftool [OPTIONS] link COMMAND
11
12          OPTIONS := { { -j | --json } [{ -p | --pretty }] | { -f | --bpffs  }
13          }
14
15          COMMANDS := { show | list | pin | help }
16

18       bpftool link { show | list } [LINK]
19       bpftool link pin LINK FILE
20       bpftool link detach LINK
21       bpftool link help
22
23       LINK := { id LINK_ID | pinned FILE }
24
25

DESCRIPTION

27          bpftool link { show | list } [LINK]
28                 Show  information  about  active  links. If LINK is specified
29                 show information only about given link,  otherwise  list  all
30                 links currently active on the system.
31
32                 Output will start with link ID followed by link type and zero
33                 or more named attributes, some of which  depend  on  type  of
34                 link.
35
36                 Since Linux 5.8 bpftool is able to discover information about
37                 processes that hold open file descriptors (FDs)  against  BPF
38                 links.  On  such kernels bpftool will automatically emit this
39                 information as well.
40
41          bpftool link pin LINK FILE
42                 Pin link LINK as FILE.
43
44                 Note: FILE must be located in bpffs mount. It must  not  con‐
45                 tain  a  dot  character  ('.'),  which is reserved for future
46                 extensions of bpffs.
47
48          bpftool link detach LINK
49                 Force-detach link LINK. BPF link and its underlying BPF  pro‐
50                 gram  will  stay  valid,  but  they will be detached from the
51                 respective BPF hook and  BPF  link  will  transition  into  a
52                 defunct  state  until last open file descriptor for that link
53                 is closed.
54
55          bpftool link help
56                 Print short help message.
57

OPTIONS

59          -h, --help
60                 Print short help message (similar to bpftool help).
61
62          -V, --version
63                 Print  version  number  (similar  to  bpftool  version),  and
64                 optional  features  that  were included when bpftool was com‐
65                 piled. Optional features include linking  against  libbfd  to
66                 provide  the  disassembler for JIT-ted programs (bpftool prog
67                 dump jited) and usage of BPF skeletons  (some  features  like
68                 bpftool  prog  profile  or  showing  pids  associated  to BPF
69                 objects may rely on it).
70
71          -j, --json
72                 Generate JSON output. For commands that cannot produce  JSON,
73                 this option has no effect.
74
75          -p, --pretty
76                 Generate human-readable JSON output. Implies -j.
77
78          -d, --debug
79                 Print  all logs available, even debug-level information. This
80                 includes logs from libbpf as well as from the verifier,  when
81                 attempting to load programs.
82
83          -f, --bpffs
84                 When showing BPF links, show file names of pinned links.
85
86          -n, --nomount
87                 Do not automatically attempt to mount any virtual file system
88                 (such as tracefs or BPF virtual file system) when necessary.
89

EXAMPLES

91       # bpftool link show
92
93          10: cgroup  prog 25
94                  cgroup_id 614  attach_type egress
95                  pids test_progs(223)
96
97       # bpftool --json --pretty link show
98
99          [{
100                  "type": "cgroup",
101                  "prog_id": 25,
102                  "cgroup_id": 614,
103                  "attach_type": "egress",
104                  "pids": [{
105                          "pid": 223,
106                          "comm": "test_progs"
107                      }
108                  ]
109              }
110          ]
111
112       # bpftool link pin id 10 /sys/fs/bpf/link
113       # ls -l /sys/fs/bpf/
114
115
116          -rw------- 1 root root 0 Apr 23 21:39 link
117

SEE ALSO

119          bpf(2),      bpf-helpers(7),       bpftool(8),       bpftool-btf(8),
120          bpftool-cgroup(8),        bpftool-feature(8),        bpftool-gen(8),
121          bpftool-iter(8),  bpftool-map(8),  bpftool-net(8),  bpftool-perf(8),
122          bpftool-prog(8), bpftool-struct_ops(8)
123
124
125
126
127                                                               BPFTOOL-LINK(8)
Impressum