即使在命令行中传递的参数中包含“未找到子字符串”

Question

I can't figure out why this is happening, so any help is appreciated.

hi.py

import httplib, urlparse, sys, urllib

url = sys.argv[1]

print url
print url.index("token")
print url.index("&user")

Then in ubuntu if I try to run something like:

python hi.py http://somewebsite.com/api?token=hello_world&user=myself

I get this as output:

http://somewebsite.com/api?token=hello_world
27
Traceback (most recent call last):
  File "hi.py", line 10, in <module>
    print url.index("&user")
ValueError: substring not found

For some reason the whole URL is not being printed, and I suspect that's why the &user substring is not found. Any ideas?

Answer 1

& is a shell meta character, which puts the command in the background . You need to quote your argument to prevent the & character from being interpreted as such:

python hi.py "http://somewebsite.com/api?token=hello_world&user=myself"

or use a \\ backslash to escape just the ampersand:

python hi.py http://somewebsite.com/api?token=hello_world\&user=myself

otherwise the shell sees this as two separate commands, with user=myself by coincidence being valid shell syntax.

Any of the following characters are special in a shell :

 \ ' " ` < > | ; <Space> <Tab> <Newline> ( ) [ ] ? # $ ^ & * =

These need to be escaped in the same way; the ? happens to work for the URL since no filenames are being matched; had you used hi.p? the filename hi.py would be substituted. The = only needs escaping when the left-hand side is a valid shell variable identifier I think, but to be safe I'd stick with quoting the whole URL.