Reading Notes on NS2(11)

数据分析

 

使用gawk分析Trace文件

[1] gawk
awk是一种程序语言。它具有一般程序语言常见的功能。
注意:
(1)awk书写程序比使用其他语言更简洁、便利且节省时间。
(2)awk善于处理具有记录(record)字段(field)等形态的数据。
(3)awk可以配合管道(pipe)一起使用。

gawk是GNU所开发的awk,最初在1986年完成,之后不断地改进和更新。gawk包含awk的所有功能。


[2] gawk读取Trace文件
记录(record)是gawk从输入文件中读取的基本单位。(一般而言,一条记录相当于数据文件中的一行数据)
字段(field)是记录被分割开的字符串。(一般而言,是以空格符来分隔相邻的字段)
注意:
(1)当gawk读入记录后,会把每个的值自动存入字段变量。

字段变量           意义
$0             内容为awk所读入的一条记录
$1             代表$0上第一个字段的数据
$2             代表$0上第二个字段的数据
...


[3] gawk程序的主要结构
gawk的主要功能是针对文件的每一条记录搜寻指定的模式(patterns)。gawk依次处理输入文件的每一条记录,直到输入文件结束为止。
注意:
(1)一般常用“关系判断式”来构造pattern。
(2)awk提供C语言常见的关系操作符。
(3)有两个特殊的pattern,分别是BEGIN和END,表示gawk在开始执行和结束时会分别执行BEGIN和END指定的action。注意!BEGIN和END中的action在整个处理过程中只执行一次,而不对每条记录都执行。


[4] gawk的基本命令

(1)IO命令
(a)print命令:用在简单、标准的输出格式。
print后面不跟东西等同于print $0,会输出当前的记录。
print "" 输出空白行。
print "Hi,wcdj" 输出一串文字。
(b)printf命令:能够精确地控制输出格式。
用法和C语言的printf相同。

(2)流程控制指令
(a)条件语句
if(x%2==0)
   print "x is even"
else
   print "x is odd"
(b)循环语句
while、for同C语言用法
(c)运算指令
运算指令包括算术运算、逻辑运算等。同C语言。


[5] gawk程序的工作流程
执行awk程序时,它会反复进行下面4个步骤:
(1)自动从指定的输入文件中读取一条记录。
(2)自动更新相关的内建变量值。
(3)逐次执行程序中所有的命令。
(4)当此记录执行完所有命令时,若还有记录则重新从(1)开始执行,直到所有记录都执行一遍。

注意:
awk会自动重复进行上述的四个步骤。


[6] gawk的执行方法
(1)如果gawk程序很短,则程序代码可以直接写在命令行上。
(2)如果gawk程序较长,则将gawk程序存为一个文件。(此方法常用)


[7] 使用gawk进行数据分析的实例

The Network Simulator, Version 3 -------------------------------- Table of Contents: ------------------ 1) An overview 2) Building ns-3 3) Running ns-3 4) Getting access to the ns-3 documentation 5) Working with the development version of ns-3 Note: Much more substantial information about ns-3 can be found at http://www.nsnam.org 1) An Open Source project ------------------------- ns-3 is a free open source project aiming to build a discrete-event network simulator targeted for simulation research and education. This is a collaborative project; we hope that the missing pieces of the models we have not yet implemented will be contributed by the community in an open collaboration process. The process of contributing to the ns-3 project varies with the people involved, the amount of time they can invest and the type of model they want to work on, but the current process that the project tries to follow is described here: http://www.nsnam.org/developers/contributing-code/ This README excerpts some details from a more extensive tutorial that is maintained at: http://www.nsnam.org/documentation/latest/ 2) Building ns-3 ---------------- The code for the framework and the default models provided by ns-3 is built as a set of libraries. User simulations are expected to be written as simple programs that make use of these ns-3 libraries. To build the set of default libraries and the example programs included in this package, you need to use the tool 'waf'. Detailed information on how use waf is included in the file doc/build.txt However, the real quick and dirty way to get started is to type the command ./waf configure --enable-examples followed by ./waf in the the directory which contains this README file. The files built will be copied in the build/ directory. The current codebase is expected to build and run on the set of platforms listed in the RELEASE_NOTES file. Other platforms may or may not work: we welcome patches to improve the portability of the code to these other platforms. 3) Running ns-3 --------------- On recent Linux systems, once you have built ns-3 (with examples enabled), it should be easy to run the sample programs with the following command, such as: ./waf --run simple-global-routing That program should generate a simple-global-routing.tr text trace file and a set of simple-global-routing-xx-xx.pcap binary pcap trace files, which can be read by tcpdump -tt -r filename.pcap The program source can be found in the examples/routing directory. 4) Getting access to the ns-3 documentation ------------------------------------------- Once you have verified that your build of ns-3 works by running the simple-point-to-point example as outlined in 4) above, it is quite likely that you will want to get started on reading some ns-3 documentation. All of that documentation should always be available from the ns-3 website: http:://www.nsnam.org/documentation/. This documentation includes: - a tutorial - a reference manual - models in the ns-3 model library - a wiki for user-contributed tips: http://www.nsnam.org/wiki/ - API documentation generated using doxygen: this is a reference manual, most likely not very well suited as introductory text: http://www.nsnam.org/doxygen/index.html 5) Working with the development version of ns-3 ----------------------------------------------- If you want to download and use the development version of ns-3, you need to use the tool 'mercurial'. A quick and dirty cheat sheet is included in doc/mercurial.txt but reading through the mercurial tutorials included on the mercurial website is usually a good idea if you are not familiar with it. If you have successfully installed mercurial, you can get a copy of the development version with the following command: "hg clone http://code.nsnam.org/ns-3-dev"
最新发布
03-08
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