11 ms·

Sure, but if the server response is not pipelined (as is probably often the case), then bash should never see anything.

mikeash 12y ago
HTTP pipelining is about reusing a TCP connection for multiple requests. It doesn't influence when curl outputs data and wouldn't apply here anyway. I don't think there's any mode which would cause curl to buffer the entire response before writing any of it.
- michaelmior 12y ago
  Yes, I'm aware of how HTTP pipelining works. It was a poor choice of terminology. My point is that by default curl does buffer some of the response. And if the connection was terminated before the first buffer was output, then I would expect this to result in an error which would abort the shell pipeline.
  - mikeash 12y ago
    Yes, in some cases curl won't produce any output, like if the web server is down, or the connection fails before anything is returned. And yes, it would also happen if curl buffers some of the response and then dies. I don't really see why that's interesting.
    - michaelmior 12y ago
      The default buffer size is typically the page size, which is typically 4096 bytes. I would expect a large number of these scripts to be less than 4096 bytes meaning curl would output nothing before producing an error and the partial script would never be evaluated.
      - mikeash 12y ago
        That's the default buffer size for pipes, which won't matter here. When curl terminates, whatever's buffered in the pipe will be flushed. The only thing that could prevent downloaded data from being received by the shell would be internal buffering in curl, if it does any.
        michaelmior 12y ago
        Good point. curl doesn't do any internal buffering. I was thinking that the pipeline should be aborted if the curl exits with a non-zero status, but of course this is not the case.
        mikeash 12y ago
        Yeah, it would be nice if there were a way for a part of the pipeline to signal that something bad happened and everything should stop. Ideally, some sort of transaction system so the script is guaranteed to run fully or not at all. But instead we have this crazy thing.

HTTP pipelining is about reusing a TCP connection for multiple requests. It doesn't influence when curl outputs data and wouldn't apply here anyway. I don't think there's any mode which would cause curl to buffer the entire response before writing any of it.

michaelmior 12y ago
Yes, I'm aware of how HTTP pipelining works. It was a poor choice of terminology. My point is that by default curl does buffer some of the response. And if the connection was terminated before the first buffer was output, then I would expect this to result in an error which would abort the shell pipeline.
- mikeash 12y ago
  Yes, in some cases curl won't produce any output, like if the web server is down, or the connection fails before anything is returned. And yes, it would also happen if curl buffers some of the response and then dies. I don't really see why that's interesting.
  - michaelmior 12y ago
    The default buffer size is typically the page size, which is typically 4096 bytes. I would expect a large number of these scripts to be less than 4096 bytes meaning curl would output nothing before producing an error and the partial script would never be evaluated.
    - mikeash 12y ago
      That's the default buffer size for pipes, which won't matter here. When curl terminates, whatever's buffered in the pipe will be flushed. The only thing that could prevent downloaded data from being received by the shell would be internal buffering in curl, if it does any.
      - michaelmior 12y ago
        Good point. curl doesn't do any internal buffering. I was thinking that the pipeline should be aborted if the curl exits with a non-zero status, but of course this is not the case.
        mikeash 12y ago
        Yeah, it would be nice if there were a way for a part of the pipeline to signal that something bad happened and everything should stop. Ideally, some sort of transaction system so the script is guaranteed to run fully or not at all. But instead we have this crazy thing.