sys.agrv

最新推荐文章于 2024-09-11 20:19:47 发布

bigsnowstorm

最新推荐文章于 2024-09-11 20:19:47 发布

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本文详细解释了Python中sys.argv的使用方法，包括如何通过sys.argv获取命令行参数，并检查参数的有效性。此外，还提供了如何优雅地处理错误输入的例子。

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http://stackoverflow.com/questions/2626026/python-sys-argv-lists-and-indexes

C:\> hello.py John

argv represents all the items that come along via the command-line input, but counting starts at zero (0) not one (1): in this case, "hello.py" is element 0, "John" is element 1

in other words, sys.argv[0] == 'hello.py' and sys.argv[1] == 'John' ... but look, how many elements is this? 2, right! so even though the numbers are 0 and 1, there are 2 elements here.

http://stackoverflow.com/questions/983201/python-and-sys-argv

if len(sys.argv) < 2:
    sys.stderr.write('Usage: sys.argv[0] ')
    sys.exit(1)


if not os.path.exists(sys.argv[1]):
    sys.stderr.write('ERROR: Database sys.argv[1] was not found!')
    sys.exit(1)

This is a portion of code I'm working on. The first part I'm trying to say if the user doesn't type.... python programname something then it will exit.

The second part I'm trying to see if the database exists.

BTW you can pass the error message directly to sys.exit:

if len(sys.argv) < 2:
    sys.exit('Usage: %s database-name' % sys.argv[0])

if not os.path.exists(sys.argv[1]):
    sys.exit('ERROR: Database %s was not found!' % sys.argv[1])