Python ARVG usage

Transferred from: http://blog.csdn.net/vivilorne/article/details/3863545

In the process of learning Python, I never understood the meaning of sys.argv[], though I knew it was a command line argument, but it was a bit of a blur.

Today, a good study of a, finally is Taichetaiwu.

Sys.argv[] is used to get command line arguments, Sys.argv[0] represents the code itself file path, so the parameters starting from 1, the following two examples illustrate:

1, using a simple example of sys.argv[],

Import Sys,os

1. Os.system (Sys.argv[1])

This example Os.system receive command line arguments, run parameter directives, save as sample1.py, command line with parameters run sample1.py Notepad, will open the Notepad program.

2, this example is a concise Python tutorial, understand it after you understand sys.argv[].

[python] view plain copy 

2. Import Sys
4. def readfile (filename): #从文件中读出文件内容
6. ' Print a file to the standard output. '
8. f = file (filename)
10. While True:
12. line = F.readline ()
14. If Len (line) = = 0:
16. Break
18. Print line, # Notice comma output each row of content separately
20. F.close ()
22. # Script starts from here
24. If Len (SYS.ARGV) < 2:
26. print ' No action specified. '
28. Sys.exit ()
30. If Sys.argv[1].startswith ('--'):
32. option = sys.argv[1][2:]
34. # fetch SYS.ARGV[1] But without the first and the characters
36. if option = = ' Version ': #当命令行参数为--version, display the revision number
38. print ' Version 1.2 '
40. elif option = = ' help ': When #当命令行参数为--help, the relevant helper content is displayed
42. Print ""/
44. Prints files to the standard output.
46. Any number of the files can be specified.
48. Options include:
50. --version:prints the version number
52. --help:display this ""
54. Else
56. print ' Unknown option. '
58. Sys.exit ()
60. Else
62. For filename in sys.argv[1:]: #当参数为文件名时, incoming ReadFile, read out its contents
64. ReadFile (filename)

Save the program as sample.py. Let's verify that:

1) command line with parameters run: Sample.py–version output is: Version 1.2

2) command line with parameters run: Sample.py–help output is: This program prints files ...

3) in the same directory as sample.py, create a new a.txt Notepad file with the content: Test argv; command line with parameters run: sample.py a.txt, the output is a.txt file content: Test argv, here can also take a few more parameters, The program will output the contents of the parameter file successively.

~~~~~~~~~~~~believe yourself, nothing was impossible, write in 02.05.2009 by vivilorne~~~~~~~~~~~~~

Python ARVG usage