[Set] collection of common Erlang commands

Reprinted: http://www.cnblogs.com/gordonchao/archive/2011/01/06.html

1.net _ ADM: names ()

2. record_info (fields, Tab)

3. Mod: module_info (attributes)

4. beam_lib: chunks ("Mod. Beam", [attributes]).

5.-vsn (1234 ).

-Author ({Gordon, Chao }).

6.Mnesia

Erl-mnesia dir'"/Home/Gordon/mnesia"' % specifies the directory when starting Erlang

Mnesia: system_info (directory). % to get the directory stored in the mnesia table

Mnesia: Info ().

Mnesia: change_table_frag (Dictionary, {activate, []}). % activate mnesia Fragment

Activate table shards: (A @ localhost) 25> mnesia: change_table_frag (Dictionary, {activate, []}).

{Atomic, OK}

Check whether the resolution is activated:

(A @ localhost) 26> mnesia: table_info (Dictionary, frag_properties ). [{base_table, Dictionary}, {foreign_key, undefined}, {hash_module, mnesia_frag_hash}, {hash_state, {hash_state, 1, 1, 0, phash2 }}, {n_fragments, 1 }, {node_pool, [A @ localhost, B @ localhost, c @ localhost]}]
Now we can add table shards. For convenience, create a function to obtain the frag_dist of the table.

(A @ localhost)28> gettableinfo = fun (item)-> mnesia: table_info (Dictionary, item) end.

# Fun <erl_eval.6.35866844>

(A @ localhost)29> getfragnodes = fun ()-> mnesia: Activity (sync_dirty, gettableinfo, [frag_dist], mnesia_frag) end. # Fun <erl_eval.10967289768>

Test:

(A @ localhost)30> getfragnodes ().

[{B @ localhost, 0}, {c @ localhost, 0}, {A @ localhost, 1}]

Now you can add a shard. Through the node list returned by getfragnodes, mnesia can add the new Shard to a relatively idle node by load balancing:

(A @ localhost)35> mnesia: change_table_frag (Dictionary, {add_frag, getfragnodes ()}). {atomic, OK}

(A @ localhost)36> mnesia: table_info (Dictionary, frag_properties ). [{base_table, Dictionary}, {foreign_key, undefined}, {hash_module, mnesia_frag_hash}, {hash_state, {hash_state, 2, 1, phash2 }}, {n_fragments, 2 }, {node_pool, [A @ localhost, B @ localhost, c @ localhost]}]

We can see {n_fragments, 2}, which has been increased to 2. Check the node to which the new part is assigned:

(A @ localhost)37> getfragnodes ().

[{C @ localhost, 0}, {A @ localhost, 1}, {B @ localhost, 1}]

We can see that each of node A and Node B has a shard, And the shard of Node B is new.

7. Erl-man ERL

Erl-man lists

8. Tool commands

TV: Start ()

Debugger: Start ()

Appmon: Start ()

Code: clash ()

Pman: Start ()

9. whereis (MOD)

10. process_info (PID, message_queue_len ).