bash wget 一起使用 --timeout 和 --trys

wget using --timeout and --tries together

提问by mickadoo

How long would you expect this command to take before exiting?

在退出之前，您预计此命令需要多长时间？

wget --timeout=1 --tries=2 "http://www.google.com:81/not-there"

wget --timeout=1 --tries=2 "http://www.google.com:81/not-there"

I would expect a timeout of 1 seconds and 2 tries would mean 2 seconds, but it takes 6.025 seconds

我希望超时 1 秒和 2 次尝试意味着 2 秒，但需要 6.025 秒

wget --timeout=1 --tries=2 "http://www.google.com:81/not-there"
--2017-04-27 16:49:12--http://www.google.com:81/not-there
Resolving www.google.com (www.google.com)... 209.85.203.105, 209.85.203.103, 209.85.203.99, ...
Connecting to www.google.com (www.google.com)|209.85.203.105|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.103|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.99|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.104|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.106|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.147|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|2a00:1450:4009:80d::2004|:81... failed: Network is unreachable.

I don't know why it tries 6 times before quitting.

我不知道为什么它在退出之前尝试了 6 次。

It seems like triesis for retrying. If I set --retry-connrefusedit at least does the retry, but still the total time taken isn't what I would expect. I'd like to be able to decide how many times it should try on a timeout.

好像tries是为了重试。如果我设置--retry-connrefused它至少会重试，但总时间仍然不是我所期望的。我希望能够决定它应该尝试多少次超时。

Edit:

编辑：

After a suggestion from @Socowi I tried using waitretry in combination with retry-connrefused and got the same behaviour:

在@Socowi 提出建议后，我尝试将 waitretry 与 retry-connrefused 结合使用并得到相同的行为：

$ wget --timeout=1 --waitretry=0 --tries=2 --retry-connrefused "http://www.google.com:81/not-there"
--2017-04-27 20:29:47--  http://www.google.com:81/not-there
Resolving www.google.com (www.google.com)... 2a00:1450:400b:c00::68, 209.85.203.99, 209.85.203.147, ...
Connecting to www.google.com (www.google.com)|2a00:1450:400b:c00::68|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.99|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.147|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.103|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.104|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.106|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.105|:81... failed: Connection timed out.
Retrying.

--2017-04-27 20:29:54--  (try: 2)  http://www.google.com:81/not-there
Connecting to www.google.com (www.google.com)|2a00:1450:400b:c00::68|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.99|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.147|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.103|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.104|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.106|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.105|:81... failed: Connection timed out.
Giving up.

Edit Two

编辑二

I was really confused when two identical commands behaved differently.

当两个相同的命令表现不同时，我真的很困惑。

root@8c59d6dd05fe:/var/www/html# wget --timeout=1 --waitretry=0 --tries=2 --retry-connrefused "http://www.google.com:81/not-there"
converted 'http://www.google.com:81/not-there' (ANSI_X3.4-1968) -> 'http://www.google.com:81/not-there' (UTF-8)
--2017-04-27 19:50:28--  http://www.google.com:81/not-there
Resolving www.google.com (www.google.com)... 216.58.211.164, 2a00:1450:4009:805::2004
Connecting to www.google.com (www.google.com)|216.58.211.164|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|2a00:1450:4009:805::2004|:81... failed: Cannot assign requested address.
Retrying.

--2017-04-27 19:50:29--  (try: 2)  http://www.google.com:81/not-there
Connecting to www.google.com (www.google.com)|216.58.211.164|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|2a00:1450:4009:805::2004|:81... failed: Cannot assign requested address.
Giving up.

root@8c59d6dd05fe:/var/www/html# wget --timeout=1 --waitretry=0 --tries=2 --retry-connrefused "http://www.google.com:81/not-there"
converted 'http://www.google.com:81/not-there' (ANSI_X3.4-1968) -> 'http://www.google.com:81/not-there' (UTF-8)
--2017-04-27 19:50:35--  http://www.google.com:81/not-there
Resolving www.google.com (www.google.com)... 209.85.203.104, 209.85.203.147, 209.85.203.106, ...
Connecting to www.google.com (www.google.com)|209.85.203.104|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.147|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.106|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.103|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.105|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.99|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|2a00:1450:400b:c03::68|:81... failed: Cannot assign requested address.
Retrying.

--2017-04-27 19:50:41--  (try: 2)  http://www.google.com:81/not-there
Connecting to www.google.com (www.google.com)|209.85.203.104|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.147|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.106|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.103|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.105|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|209.85.203.99|:81... failed: Connection timed out.
Connecting to www.google.com (www.google.com)|2a00:1450:400b:c03::68|:81... failed: Cannot assign requested address.
Giving up.

I thought I was going a bit crazy, but it was only when @Socowi pointed out in the comments that the IPs each retry were different that it clicked. It depends on the number of possible IPs being returned. The magic number 7 (retries) I was seeing was number the IP options. When I just choose one specific IP it only tries it once.

我以为我有点疯了，但只有当@Socowi 在评论中指出每次重试的 IP 不同时才点击。这取决于返回的可能 IP 的数量。我看到的神奇数字 7（重试）是 IP 选项的编号。当我只选择一个特定的 IP 时，它只会尝试一次。

回答by Socowi

Wrong Number of Retries

错误的重试次数

Your wget seems to resolve the URL to multiple IP addresses as seen in the second line of your wget's output. Each IP is then tested with the specified timeout. Unfortunately I haven't found any options to limit the DNS lookup to one address or set a total timeout for all IPs together. But you could try to use "<googles ip address>:81/not-there"instead of the URL.

您的 wget 似乎将 URL 解析为多个 IP 地址，如您wget输出的第二行所示。然后使用指定的超时测试每个 IP。不幸的是，我没有找到任何选项来将 DNS 查找限制为一个地址或为所有 IP 设置总超时。但是您可以尝试使用"<googles ip address>:81/not-there"代替 URL。

Seemingly Too Long Timeout

看似过长的超时

As you already found out, setting --retry-connrefusedlets wgetretry even after a ?connection refused? error. The specified timeout is used for each retry, but between the retries there will be a pause which gets longer after each retry.

正如你已经发现，设置--retry-connrefused让wget即使重试？连接被拒绝？错误。每次重试都使用指定的超时时间，但在重试之间会有一个暂停，每次重试后都会变得更长。

Example

例子

wget --timeout=1 --tries=5 --retry-connrefused URL

does something like

做类似的事情

try to connect for 1 second
failed -> wait 1 second
try to connect for 1 second
failed -> wait 2 seconds
try to connect for 1 second
failed -> wait 3 second
try to connect for 1 second
failed -> wait 4 second
try to connect for 1 second

Therefore the command takes tries * timeout + 1 + 2 + ... + (tries - 1)seconds. This behavior is specified in man wgetunder the option, which allows you to change it :)

因此该命令需要tries * timeout + 1 + 2 + ... + (tries - 1)几秒钟。此行为man wget在选项下指定，它允许您更改它:)

--waitretry=seconds
If you don't want Wget to wait between every retrieval, but only between retries of failed downloads, you can use this option. Wget will use linear backoff, waiting 1 second after the first failure on a given file, then waiting 2 seconds after the second failure on that file, up to the maximum number of seconds you specify.

By default, Wget will assume a value of 10 seconds.

--waitretry=seconds
如果您不希望 Wget 在每次检索之间等待，而只在下载失败的重试之间等待，则可以使用此选项。Wget 将使用线性退避，在给定文件第一次失败后等待 1 秒，然后在该文件第二次失败后等待 2 秒，直到您指定的最大秒数。

默认情况下，Wget 将假定值为 10 秒。

I think you wanted to use something like

我想你想使用类似的东西

wget --timeout=1 --waitretry=0 --tries=5 --retry-connrefused URL

which eliminates the pause between two retries, resulting in a total time of timeout * tries.

这消除了两次重试之间的暂停，导致总时间为timeout * tries.