英文:
Why does reading from file descriptor 3 hangs with bash and network redirection?
问题
以下是翻译好的部分：
我正在使用bash和网络重定向发送HTTP请求。
这是我发送的请求：
exec 3<> $initial_url
path="/webhdfs/v1$hdfs_target?user.name=hdfs&op=OPEN"
printf "GET $path HTTP/1.1\r\nHost: $url:$port\r\nAccept: */*\r\n\r\n" >&3
echo toto
cat <&3
echo titi
exec 3<&
我已经正确接收到响应。然而，`cat` 永远不会结束。以下是执行输出（通过ctrl+c终止）：
$ time bash toto.sh
toto
HTTP/1.1 307 TEMPORARY_REDIRECT
Cache-Control: no-cache
Expires: Thu, 20 Jul 2023 12:29:41 GMT
Date: Thu, 20 Jul 2023 12:29:41 GMT
Pragma: no-cache
Expires: Thu, 20 Jul 2023 12:29:41 GMT
Date: Thu, 20 Jul 2023 12:29:41 GMT
Pragma: no-cache
X-FRAME-OPTIONS: SAMEORIGIN
Set-Cookie: hadoop.auth="redacted_for_SO"; Path=/; HttpOnly
Location: redacted_for_SO
Content-Type: application/octet-stream
Content-Length: 0
real 0m19.042s
user 0m0.124s
sys 0m0.733s
这个输出包含我需要的一切，但正如所说，`cat` 永远不会结束。
- 为什么`cat` 挂起？它在等待什么？
- 当数据已接收时，如何防止它挂起？
英文:
I am using bash and network redirection to send HTTP requests.
Here is the request I am sending:
exec 3<> $initial_url
path="/webhdfs/v1$hdfs_target?user.name=hdfs&op=OPEN"
printf "GET $path HTTP/1.1\r\nHost: $url:$port\r\nAccept: */*\r\n\r\n" >&3
echo toto
cat <&3
echo titi
exec 3<&
I am recieving the response correctly. However, the cat just hangs indefinitely. Here is an execution output (killed with ctrl+c):
$ time bash toto.sh
toto
HTTP/1.1 307 TEMPORARY_REDIRECT
Cache-Control: no-cache
Expires: Thu, 20 Jul 2023 12:29:41 GMT
Date: Thu, 20 Jul 2023 12:29:41 GMT
Pragma: no-cache
Expires: Thu, 20 Jul 2023 12:29:41 GMT
Date: Thu, 20 Jul 2023 12:29:41 GMT
Pragma: no-cache
X-FRAME-OPTIONS: SAMEORIGIN
Set-Cookie: hadoop.auth="redacted_for_SO"; Path=/; HttpOnly
Location: redacted_for_SO
Content-Type: application/octet-stream
Content-Length: 0
real 0m19.042s
user 0m0.124s
sys 0m0.733s
There is everything I need in this output, but as said, the cat never ends.
- Why is the cat hanging ? What is it waiting for ?
- How to prevent it from hanging when the data has been recieved ?
答案1
得分: 2
你应该在你的请求中添加一个Connection: close头部，这样服务器在发送完响应后会关闭连接。另请参阅这里：https://serverfault.com/questions/790197/what-does-connection-close-mean-when-used-in-the-response-message
英文:
You should add a Connection: close header to your request so that the server will close the connection once it's finished sending the response. See also here: https://serverfault.com/questions/790197/what-does-connection-close-mean-when-used-in-the-response-message
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