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

bpftoollink{show|list}[LINK]
              Show  information about active links. If LINK is specified show information only about given link,
              otherwise list all links currently active on the system.

              Output will start with link ID followed by link type and zero or more named  attributes,  some  of
              which depend on type of link.

              Since  Linux  5.8  bpftool  is  able  to  discover information about processes that hold open file
              descriptors (FDs) against BPF  links.  On  such  kernels  bpftool  will  automatically  emit  this
              information as well.

       bpftoollinkpinLINKFILE
              Pin link LINK as FILE.

              Note:  FILE  must  be  located in bpffs mount. It must not contain a dot character ('.'), which is
              reserved for future extensions of bpffs.

       bpftoollinkdetachLINK
              Force-detach link LINK. BPF link and its underlying BPF program will stay valid, but they will  be
              detached from the respective BPF hook and BPF link will transition into a defunct state until last
              open file descriptor for that link is closed.

       bpftoollinkhelp
              Print short help message.

#bpftoollinkshow

          10: cgroup  prog 25
                  cgroup_id 614  attach_type egress
                  pids test_progs(223)

       #bpftool--json--prettylinkshow

          [{
                  "type": "cgroup",
                  "prog_id": 25,
                  "cgroup_id": 614,
                  "attach_type": "egress",
                  "pids": [{
                          "pid": 223,
                          "comm": "test_progs"
                      }
                  ]
              }
          ]

       #bpftoollinkpinid10/sys/fs/bpf/link#ls-l/sys/fs/bpf/

          -rw------- 1 root root 0 Apr 23 21:39 link

bpftoollink{show|list} [LINK]
       bpftoollinkpinLINKFILEbpftoollinkdetachLINKbpftoollinkhelpLINK := { idLINK_ID | pinnedFILE }

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

-h, --help
                 Print short help message (similar to bpftoolhelp).

          -V, --version
                 Print  bpftool's  version number (similar to bpftoolversion), the number of the libbpf version
                 in use, and optional features that were included when bpftool was compiled.  Optional  features
                 include  linking  against  LLVM  or  libbfd  to  provide  the disassembler for JIT-ted programs
                 (bpftoolprogdumpjited) and usage of BPF skeletons (some features like bpftoolprogprofile
                 or showing pids associated to BPF objects may rely on it).

          -j, --json
                 Generate JSON output. For commands that cannot produce JSON, this option has no effect.

          -p, --pretty
                 Generate human-readable JSON output. Implies -j.

          -d, --debug
                 Print  all logs available, even debug-level information. This includes logs from libbpf as well
                 as from the verifier, when attempting to load programs.

          -f, --bpffs
                 When showing BPF links, show file names of pinned links.

          -n, --nomount
                 Do not automatically attempt to mount any virtual file system (such as tracefs or  BPF  virtual
                 file system) when necessary.

bpf(2),    bpf-helpers(7),    bpftool(8),    bpftool-btf(8),    bpftool-cgroup(8),    bpftool-feature(8),
       bpftool-gen(8),  bpftool-iter(8),  bpftool-map(8),  bpftool-net(8),   bpftool-perf(8),   bpftool-prog(8),
       bpftool-struct_ops(8)

                                                                                                 BPFTOOL-LINK(8)

bpftool [OPTIONS] linkCOMMANDOPTIONS := { { -j | --json } [{ -p | --pretty }] | { -d | --debug } | { -f | --bpffs } | { -n | --nomount
       } }

       COMMANDS := { show | list | pin | help }