接前一篇文章：BCC源码内容概览（2）
本文参考官网中的Contents部分的介绍。
BCC源码根目录的文件，其中一些是同时包含C和Python的单个文件，另一些是.c和.py的成对文件，还有一些是目录。
跟踪（Tracing）
examples目录下的文件：
- examples/tracing/task_switch.py
从PIDs切换出和切换到的任务切换计数。
- examples/tracing/tcpv4connect.py
跟踪TCP IPv4活动连接。
bcc/examples/tracing/tcpv4connect_example.txt文件内容如下：
Demonstrations of tcpv4connect.py, the Linux eBPF/bcc version.
This example traces the kernel function performing active TCP IPv4 connections
(eg, via a connect() syscall; accept() are passive connections). Some example
output (IP addresses changed to protect the innocent):
# ./tcpv4connect.py
PID COMM SADDR DADDR DPORT
1479 telnet 127.0.0.1 127.0.0.1 23
1469 curl 10.201.219.236 54.245.105.25 80
1469 curl 10.201.219.236 54.67.101.145 80
This output shows three connections, one from a "telnet" process and two from
"curl". The output details shows the source address, destination address,
and destination port. This traces attempted connections: these may have failed.
The overhead of this tool should be negligible, since it is only tracing the
kernel function performing a connect. It is not tracing every packet and then
filtering.
This is provided as a basic example of TCP tracing. See tools/tcpconnect for a
more featured version of this example (a tool).- examples/tracing/trace_fields.py
打印跟踪事件中的字段的简单示例。
- examples/tracing/undump.py
转储UNIX套接字包。
bcc/examples/tracing/tundump_example.txt文件内容如下：
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Demonstrations of undump.py, the Linux eBPF/bcc version.
This example trace the kernel function performing receive AP_UNIX socket
packet. Some example output:
Terminal 1, UNIX Socket Server:
```
$ nc -lU /var/tmp/dsocket
# receive from Client
Hello, World
abcdefg
```
Terminal 2, UNIX socket Client:
```
$ nc -U /var/tmp/dsocket
# Input some lines
Hello, World
abcdefg
```
Terminal 3, receive tracing:
```
$ sudo python undump.py -p 49264
Tracing PID=49264 UNIX socket packets ... Hit Ctrl-C to end
# Here print bytes of receive
PID 49264 Recv 13 bytes
48 65 6c 6c 6f 2c 20 57 6f 72 6c 64 0a
PID 49264 Recv 8 bytes
61 62 63 64 65 66 67 0a
```
This output shows two packet received by PID 49264(nc -lU /var/tmp/dsocket),
`Hello, World` will be parsed as `48 65 6c 6c 6f 2c 20 57 6f 72 6c 64 0a`, the
`0a` is `Enter`. `abcdefg` will be parsed as `61 62 63 64 65 66 67 0a`.