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bpftool [OPTIONS] iter COMMAND
OPTIONS := { |COMMON_OPTIONS| }
COMMANDS := { pin | help }
- 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.
# 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