以上的就是Awk语言的核心内容。我这里没有大量的例子，因为我趋向于使用Awk来完成快速的一次性任务。

不过我依然有一些随身携带的脚本文件，用来处理一些事情和测试。我最喜欢的一个脚本是用来处理Erlang的崩溃转储文件，形如下面的：

1. =erl_crash_dump:0.3
2. Tue Nov 18 02:52:44 2014
3. Slogan: init terminating in do_boot ()
4. System version: Erlang/OTP 17 [erts-6.2] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false]
5. Compiled: Fri Sep 19 03:23:19 2014
6. Taints:
7. Atoms: 12167
8. =memory
9. total: 19012936
10. processes: 4327912
11. processes_used: 4319928
12. system: 14685024
13. atom: 339441
14. atom_used: 331087
15. binary: 1367680
16. code: 8384804
17. ets: 382552
18. =hash_table:atom_tab
19. size: 9643
20. used: 6949
21. ...
22. =allocator:instr
23. option m: false
24. option s: false
25. option t: false
26. =proc:<0.0.0>
27. State: Running
28. Name: init
29. Spawned as: otp_ring0:start/2
30. Run queue: 0
31. Spawned by: []
32. Started: Tue Nov 18 02:52:35 2014
33. Message queue length: 0
34. Number of heap fragments: 0
35. Heap fragment data: 0
36. Link list: [<0.3.0>, <0.7.0>, <0.6.0>]
37. Reductions: 29265
38. Stack+heap: 1598
39. OldHeap: 610
40. Heap unused: 656
41. OldHeap unused: 468
42. Memory: 18584
43. Program counter: 0x00007f42f9566200 (init:boot_loop/2 + 64)
44. CP: 0x0000000000000000 (invalid)
45. =proc:<0.3.0>
46. State: Waiting
47. ...
48. =port:#Port<0.0>
49. Slot: 0
50. Connected: <0.3.0>
51. Links: <0.3.0>
52. Port controls linked-in driver: efile
53. =port:#Port<0.14>
54. Slot: 112
55. Connected: <0.3.0>
56. ...

产生下面的结果：

1. $ awk -f queue_fun.awk $PATH_TO_DUMP
2. MESSAGE QUEUE LENGTH: CURRENT FUNCTION
3. ======================================
4. 10641: io:wait_io_mon_reply/2
5. 12646: io:wait_io_mon_reply/2
6. 32991: io:wait_io_mon_reply/2
7. 2183837: io:wait_io_mon_reply/2
8. 730790: io:wait_io_mon_reply/2
9. 80194: io:wait_io_mon_reply/2
10. ...

这是在Erlang进程里运行的函数列表，它们导致了mailboxe变得很庞大。脚本在这：

1. # Parse Erlang Crash Dumps and correlate mailbox size to the currently running
2. # function.
3. #
4. # Once in the procs section of the dump, all processes are displayed with
5. # =proc:<0.M.N> followed by a list of their attributes, which include the
6. # message queue length and the program counter (what code is currently
7. # executing).
8. #
9. # Run as:
10. #
11. # $ awk -v threshold=$THRESHOLD -f queue_fun.awk $CRASHDUMP
12. #
13. # Where $THRESHOLD is the smallest mailbox you want inspects. Default value
14. # is 1000.
15. BEGIN {
16. if (threshold == "") {
17. threshold = 1000 # default mailbox size
18. }
19. procs = 0 # are we in the =procs entries?
20. print "MESSAGE QUEUE LENGTH: CURRENT FUNCTION"
21. print "======================================"
22. }
23.  
24. # Only bother with the =proc: entries. Anything else is useless.
25. procs == 0 && /^=proc/ { procs = 1 } # entering the =procs entries
26. procs == 1 && /^=/ && !/^=proc/ { exit 0 } # we're done
27.  
28. # Message queue length: 1210
29. # 1 2 3 4
30. /^Message queue length: / && $4 >= threshold { flag=1; ct=$4 }
31. /^Message queue length: / && $4 < threshold { flag=0 }
32.  
33. # Program counter: 0x00007f5fb8cb2238 (io:wait_io_mon_reply/2 + 56)
34. # 1 2 3 4 5 6
35. flag == 1 && /^Program counter: / { print ct ":", substr($4,2) }

你跟上思路没？如果跟上了，你已经了解了Awk。恭喜！